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Common Weakness Enumeration

CWE-295

Allowed

Improper Certificate Validation

Abstraction: Base · Status: Draft

The product does not validate, or incorrectly validates, a certificate.

2057 vulnerabilities reference this CWE, most recent first.

GHSA-4MV8-3862-HGHV

Vulnerability from github – Published: 2022-06-16 00:00 – Updated: 2022-06-25 00:01
VLAI
Details

The httplib and urllib Python libraries that Splunk shipped with Splunk Enterprise did not validate certificates using the certificate authority (CA) certificate stores by default in Splunk Enterprise versions before 9.0 and Splunk Cloud Platform versions before 8.2.2203. Python 3 client libraries now verify server certificates by default and use the appropriate CA certificate stores for each library. Apps and add-ons that include their own HTTP libraries are not affected. For Splunk Enterprise, update to Splunk Enterprise version 9.0 and Configure TLS host name validation for Splunk-to-Splunk communications (https://docs.splunk.com/Documentation/Splunk/9.0.0/Security/EnableTLSCertHostnameValidation) to enable the remediation.

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{
  "affected": [],
  "aliases": [
    "CVE-2022-32151"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2022-06-15T17:15:00Z",
    "severity": "CRITICAL"
  },
  "details": "The httplib and urllib Python libraries that Splunk shipped with Splunk Enterprise did not validate certificates using the certificate authority (CA) certificate stores by default in Splunk Enterprise versions before 9.0 and Splunk Cloud Platform versions before 8.2.2203. Python 3 client libraries now verify server certificates by default and use the appropriate CA certificate stores for each library. Apps and add-ons that include their own HTTP libraries are not affected. For Splunk Enterprise, update to Splunk Enterprise version 9.0 and Configure TLS host name validation for Splunk-to-Splunk communications (https://docs.splunk.com/Documentation/Splunk/9.0.0/Security/EnableTLSCertHostnameValidation) to enable the remediation.",
  "id": "GHSA-4mv8-3862-hghv",
  "modified": "2022-06-25T00:01:03Z",
  "published": "2022-06-16T00:00:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-32151"
    },
    {
      "type": "WEB",
      "url": "https://docs.splunk.com/Documentation/Splunk/9.0.0/Security/EnableTLSCertHostnameValidation"
    },
    {
      "type": "WEB",
      "url": "https://docs.splunk.com/Documentation/Splunk/9.0.0/Security/Updates"
    },
    {
      "type": "WEB",
      "url": "https://research.splunk.com/application/splunk_protocol_impersonation_weak_encryption_simplerequest"
    },
    {
      "type": "WEB",
      "url": "https://www.splunk.com/en_us/product-security/announcements/svd-2022-0601.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-4MWG-64W4-5G5M

Vulnerability from github – Published: 2023-12-21 12:30 – Updated: 2024-01-04 15:30
VLAI
Details

Improper validation of the server’s certificate chain in secure traffic scanning feature considered intermediate certificate signed using the MD5 or SHA1 algorithm as trusted.

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{
  "affected": [],
  "aliases": [
    "CVE-2023-5594"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-12-21T12:15:08Z",
    "severity": "HIGH"
  },
  "details": "Improper validation of the server\u2019s certificate chain in secure traffic scanning feature considered intermediate certificate signed using the MD5 or SHA1 algorithm as trusted.",
  "id": "GHSA-4mwg-64w4-5g5m",
  "modified": "2024-01-04T15:30:21Z",
  "published": "2023-12-21T12:30:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-5594"
    },
    {
      "type": "WEB",
      "url": "https://support.eset.com/en/ca8562-eset-customer-advisory-improper-following-of-a-certificates-chain-of-trust-in-eset-security-products-fixed"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-4P6C-FXCR-RHM3

Vulnerability from github – Published: 2022-05-13 01:35 – Updated: 2022-05-13 01:35
VLAI
Details

A vulnerability in the certificate management subsystem of Cisco AnyConnect Network Access Manager and of Cisco AnyConnect Secure Mobility Client for iOS, Mac OS X, Android, Windows, and Linux could allow an unauthenticated, remote attacker to bypass the TLS certificate check when downloading certain configuration files. The vulnerability is due to improper use of Simple Certificate Enrollment Protocol and improper server certificate validation. An attacker could exploit this vulnerability by preparing malicious profile and localization files for Cisco AnyConnect to use. A successful exploit could allow the attacker to remotely change the configuration profile, a certificate, or the localization data used by AnyConnect Secure Mobility Client. Cisco Bug IDs: CSCvh23141.

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{
  "affected": [],
  "aliases": [
    "CVE-2018-0334"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2018-06-07T21:29:00Z",
    "severity": "MODERATE"
  },
  "details": "A vulnerability in the certificate management subsystem of Cisco AnyConnect Network Access Manager and of Cisco AnyConnect Secure Mobility Client for iOS, Mac OS X, Android, Windows, and Linux could allow an unauthenticated, remote attacker to bypass the TLS certificate check when downloading certain configuration files. The vulnerability is due to improper use of Simple Certificate Enrollment Protocol and improper server certificate validation. An attacker could exploit this vulnerability by preparing malicious profile and localization files for Cisco AnyConnect to use. A successful exploit could allow the attacker to remotely change the configuration profile, a certificate, or the localization data used by AnyConnect Secure Mobility Client. Cisco Bug IDs: CSCvh23141.",
  "id": "GHSA-4p6c-fxcr-rhm3",
  "modified": "2022-05-13T01:35:23Z",
  "published": "2022-05-13T01:35:23Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2018-0334"
    },
    {
      "type": "WEB",
      "url": "https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180606-AnyConnect-cert-bypass"
    },
    {
      "type": "WEB",
      "url": "http://www.securityfocus.com/bid/104430"
    },
    {
      "type": "WEB",
      "url": "http://www.securitytracker.com/id/1041075"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-4P8G-WMMC-P9F7

Vulnerability from github – Published: 2022-05-24 17:08 – Updated: 2024-03-07 21:30
VLAI
Details

Improper Certificate Validation in Node.js 10, 12, and 13 causes the process to abort when sending a crafted X.509 certificate

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{
  "affected": [],
  "aliases": [
    "CVE-2019-15604"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2020-02-07T15:15:00Z",
    "severity": "MODERATE"
  },
  "details": "Improper Certificate Validation in Node.js 10, 12, and 13 causes the process to abort when sending a crafted X.509 certificate",
  "id": "GHSA-4p8g-wmmc-p9f7",
  "modified": "2024-03-07T21:30:19Z",
  "published": "2022-05-24T17:08:13Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-15604"
    },
    {
      "type": "WEB",
      "url": "https://hackerone.com/reports/746733"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/errata/RHSA-2020:0573"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/errata/RHSA-2020:0579"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/errata/RHSA-2020:0597"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/errata/RHSA-2020:0598"
    },
    {
      "type": "WEB",
      "url": "https://access.redhat.com/errata/RHSA-2020:0602"
    },
    {
      "type": "WEB",
      "url": "https://nodejs.org/en/blog/release/v10.19.0"
    },
    {
      "type": "WEB",
      "url": "https://nodejs.org/en/blog/release/v12.15.0"
    },
    {
      "type": "WEB",
      "url": "https://nodejs.org/en/blog/release/v13.8.0"
    },
    {
      "type": "WEB",
      "url": "https://nodejs.org/en/blog/vulnerability/february-2020-security-releases"
    },
    {
      "type": "WEB",
      "url": "https://security.gentoo.org/glsa/202003-48"
    },
    {
      "type": "WEB",
      "url": "https://security.netapp.com/advisory/ntap-20200221-0004"
    },
    {
      "type": "WEB",
      "url": "https://www.debian.org/security/2020/dsa-4669"
    },
    {
      "type": "WEB",
      "url": "https://www.oracle.com//security-alerts/cpujul2021.html"
    },
    {
      "type": "WEB",
      "url": "https://www.oracle.com/security-alerts/cpuapr2020.html"
    },
    {
      "type": "WEB",
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00008.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-4PC6-W92R-32XW

Vulnerability from github – Published: 2026-06-12 03:31 – Updated: 2026-06-23 15:32
VLAI
Details

Idira Privilege Cloud Connector versions prior 1.1.100504 under specific conditions and configuration scenarios, TLS certificate validation may not be fully enforced. CyberArk Security Bulletin: CA26-17

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{
  "affected": [],
  "aliases": [
    "CVE-2026-45170"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-12T02:16:42Z",
    "severity": "HIGH"
  },
  "details": "Idira Privilege Cloud Connector versions prior 1.1.100504 under specific conditions and configuration scenarios, TLS certificate validation may not be fully enforced. CyberArk Security Bulletin: CA26-17",
  "id": "GHSA-4pc6-w92r-32xw",
  "modified": "2026-06-23T15:32:30Z",
  "published": "2026-06-12T03:31:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45170"
    },
    {
      "type": "WEB",
      "url": "https://docs.cyberark.com"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-4PJ9-G833-QX53

Vulnerability from github – Published: 2026-07-28 14:29 – Updated: 2026-07-28 14:29
VLAI
Summary
lettre has TLS hostname verification disabled when using Boring TLS backend
Details

Summary

An inverted-boolean bug in lettre's boring-tls integration silently disables TLS hostname verification for callers using the default (strict) configuration. An on-path attacker presenting any chain-valid certificate for any domain can intercept SMTP submission, including PLAIN/LOGIN credentials and message contents, against any lettre user built with the boring-tls feature. Other TLS backends (native-tls, rustls) are unaffected.

Details

boring's SslConnectorBuilder::set_verify_hostname(bool) / verify_hostname(bool) API takes a verify flag — true means enforce hostname verification, false means skip it. (Boring docs: https://docs.rs/boring/latest/boring/ssl/struct.ConnectConfiguration.html#method.set_verify_hostname) lettre's TlsParametersBuilder exposes the opposite-named flag accept_invalid_hostnames: booltrue means accept invalid (skip verification), false means verify. lettre passes this flag directly to boring at both TLS-upgrade sites, inverting the semantics: src/transport/smtp/client/net.rs:202 (sync) .verify_hostname(accept_invalid_hostnames) src/transport/smtp/client/async_net.rs:377 (async) config.set_verify_hostname(accept_invalid_hostnames); Concrete behaviour under boring-tls: * accept_invalid_hostnames = false (the strict default) → set_verify_hostname(false) → hostname verification SKIPPED (wrong; the caller asked for strict verification) * accept_invalid_hostnames = true (explicit opt-in to "dangerous") → set_verify_hostname(true) → hostname verification ENFORCED (wrong; the caller opted into accepting any name) Boring's own warning on set_verify_hostname: "If hostname verification is not used, any valid certificate for any site will be trusted for use from any other. This introduces a significant vulnerability to man-in-the-middle attacks." native-tls (src/transport/smtp/client/tls.rs:355) uses danger_accept_invalid_hostnames(self.accept_invalid_hostnames), whose flag name and semantics match lettre's — unaffected. rustls uses a separate verifier path — unaffected. The bug was introduced in PR #797 ("Add support for boring TLS"), commit 985fa7e, first released in v0.10.1, and persists unchanged through v0.11.21 (latest). Zero existing tests cover accept_invalid_hostnames end-to-end with any backend, which is why the inversion has gone undetected. Fix: negate the flag at both call sites. Two-line patch: - .verify_hostname(accept_invalid_hostnames) + .verify_hostname(!*accept_invalid_hostnames) - config.set_verify_hostname(accept_invalid_hostnames); + config.set_verify_hostname(!accept_invalid_hostnames); I have the patch ready locally and can push to a private fork if a collaborative fix branch is preferred.

PoC

Setup (any lettre version >= v0.10.1, built with the boring-tls feature, default-strict configuration): 1. Generate a TLS cert for any hostname the attacker controls, e.g. attacker.example, signed by any CA in the client's trust store (e.g. a Let's Encrypt cert is sufficient). 2. Stand up an attacker SMTP server on the network path between the lettre client and the intended MX. Have it present the attacker.example cert on STARTTLS or implicit TLS. 3. Use lettre with default-strict TLS to send to the real MX hostname, e.g. mail.example.com: use lettre::transport::smtp::client::{Tls, TlsParameters}; use lettre::{AsyncSmtpTransport, Tokio1Executor, Message}; let tls = TlsParameters::builder("mail.example.com".to_owned()) .build_boring() .unwrap(); let mailer = AsyncSmtpTransport::::relay( "mail.example.com", )? .tls(Tls::Required(tls)) .build(); mailer.send(message).await?; // succeeds against attacker Expected with hostname verification: handshake fails because the presented leaf cert's SAN does not match mail.example.com. Actual on boring-tls: handshake succeeds. lettre proceeds with the SMTP transaction, sending MAIL FROM, RCPT TO, message body, and any configured SMTP AUTH credentials to the attacker. Symmetric inverse PoC (proves the inversion, not just a missing check): configure .dangerous_accept_invalid_hostnames(true) and try to connect to a server whose cert SAN matches the connect domain. With the bug, the handshake fails because lettre passes true to verify_hostname and boring rejects... actually wait, it succeeds (SAN matches). Better inverse demonstration: connect to a server whose cert SAN matches the connect domain with accept_invalid_hostnames=true, then connect to a mismatched-SAN server with the same flag — the latter is rejected, proving the flag is inverted (the user opted into accepting any name, yet lettre enforces strict verification). A reproducer cargo project can be produced on request.

Impact

Who is impacted: any lettre user who 1. enables the boring-tls feature, AND 2. relies on default-strict hostname verification (i.e. does NOT call .dangerous_accept_invalid_hostnames(true)). This is the entire "I want strict TLS" population on boring-tls. They get the opposite of what they asked for: a TLS handshake that ignores hostname mismatch. Exploitation: an attacker on the network path between the lettre client and the target SMTP server, holding any chain-valid TLS certificate (e.g. a free Let's Encrypt cert for a domain the attacker owns), can present that certificate when the lettre client connects to the intended MX. boring accepts the handshake, lettre proceeds, and the attacker gains read/write access to: * SMTP envelope (MAIL FROM, RCPT TO) * Message bodies, attachments, headers * Any SMTP AUTH credentials (PLAIN, LOGIN, CRAM-MD5, etc.) * Any DKIM signatures and DMARC alignment downstream depends on can be inspected and selectively dropped Confidentiality and integrity impact: High. Availability impact: None direct (the attacker can choose to forward or drop, but the bug itself does not deny service). Cloudflare's email-fwdr independently identified and mitigated this downstream by promoting a previously-metric-only post-handshake SAN check to a hard error (fix landed 2026-05-12). Because we're mitigated downstream, we are not on a publication clock; we are reporting so the upstream fix can ship and other lettre+boring-tls deployments can stop relying on per-caller workarounds. Happy to coordinate on embargo timing. Affected versions: every released lettre version with boring-tls support, from v0.10.1 (PR #797, commit 985fa7e) through v0.11.21 (latest). No prior advisory or fix. Suggested fix: two-line negation of the flag at the boring call sites (see Details). Patch is ready locally and can be attached to a private collaboration fork.

Show details on source website

{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "lettre"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.10.1"
            },
            {
              "fixed": "0.11.22"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-46428"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-28T14:29:10Z",
    "nvd_published_at": "2026-07-20T16:17:01Z",
    "severity": "CRITICAL"
  },
  "details": "### Summary\nAn inverted-boolean bug in lettre\u0027s `boring-tls` integration silently\ndisables TLS hostname verification for callers using the default (strict)\nconfiguration. An on-path attacker presenting any chain-valid certificate\nfor any domain can intercept SMTP submission, including PLAIN/LOGIN\ncredentials and message contents, against any lettre user built with the\n`boring-tls` feature. Other TLS backends (`native-tls`, `rustls`) are\nunaffected.\n\n### Details\nboring\u0027s `SslConnectorBuilder::set_verify_hostname(bool)` /\n`verify_hostname(bool)` API takes a *verify* flag \u2014 `true` means enforce\nhostname verification, `false` means skip it. (Boring docs:\nhttps://docs.rs/boring/latest/boring/ssl/struct.ConnectConfiguration.html#method.set_verify_hostname)\nlettre\u0027s `TlsParametersBuilder` exposes the opposite-named flag\n`accept_invalid_hostnames: bool` \u2014 `true` means *accept invalid* (skip\nverification), `false` means verify. lettre passes this flag directly to\nboring at both TLS-upgrade sites, inverting the semantics:\nsrc/transport/smtp/client/net.rs:202 (sync)\n    .verify_hostname(*accept_invalid_hostnames)\nsrc/transport/smtp/client/async_net.rs:377 (async)\n    config.set_verify_hostname(accept_invalid_hostnames);\nConcrete behaviour under `boring-tls`:\n  * accept_invalid_hostnames = false  (the strict default)\n      \u2192 set_verify_hostname(false)  \u2192 hostname verification SKIPPED\n        (wrong; the caller asked for strict verification)\n  * accept_invalid_hostnames = true   (explicit opt-in to \"dangerous\")\n      \u2192 set_verify_hostname(true)   \u2192 hostname verification ENFORCED\n        (wrong; the caller opted into accepting any name)\nBoring\u0027s own warning on `set_verify_hostname`:\n    \"If hostname verification is not used, *any* valid certificate for\n    *any* site will be trusted for use from any other. This introduces\n    a significant vulnerability to man-in-the-middle attacks.\"\n`native-tls` (src/transport/smtp/client/tls.rs:355) uses\n`danger_accept_invalid_hostnames(self.accept_invalid_hostnames)`, whose\nflag name and semantics match lettre\u0027s \u2014 unaffected. `rustls` uses a\nseparate verifier path \u2014 unaffected.\nThe bug was introduced in PR #797 (\"Add support for boring TLS\"), commit\n985fa7e, first released in v0.10.1, and persists unchanged through v0.11.21\n(latest). Zero existing tests cover `accept_invalid_hostnames` end-to-end\nwith any backend, which is why the inversion has gone undetected.\nFix: negate the flag at both call sites. Two-line patch:\n    -    .verify_hostname(*accept_invalid_hostnames)\n    +    .verify_hostname(!*accept_invalid_hostnames)\n    -    config.set_verify_hostname(accept_invalid_hostnames);\n    +    config.set_verify_hostname(!accept_invalid_hostnames);\nI have the patch ready locally and can push to a private fork if a\ncollaborative fix branch is preferred.\n\n### PoC\nSetup (any lettre version \u003e= v0.10.1, built with the `boring-tls`\nfeature, default-strict configuration):\n1. Generate a TLS cert for any hostname the attacker controls, e.g.\n   `attacker.example`, signed by any CA in the client\u0027s trust store\n   (e.g. a Let\u0027s Encrypt cert is sufficient).\n2. Stand up an attacker SMTP server on the network path between the\n   lettre client and the intended MX. Have it present the\n   `attacker.example` cert on STARTTLS or implicit TLS.\n3. Use lettre with default-strict TLS to send to the real MX hostname,\n   e.g. `mail.example.com`:\n       use lettre::transport::smtp::client::{Tls, TlsParameters};\n       use lettre::{AsyncSmtpTransport, Tokio1Executor, Message};\n       let tls = TlsParameters::builder(\"mail.example.com\".to_owned())\n           .build_boring()\n           .unwrap();\n       let mailer = AsyncSmtpTransport::\u003cTokio1Executor\u003e::relay(\n               \"mail.example.com\",\n           )?\n           .tls(Tls::Required(tls))\n           .build();\n       mailer.send(message).await?;     // succeeds against attacker\nExpected with hostname verification: handshake fails because the\npresented leaf cert\u0027s SAN does not match `mail.example.com`.\nActual on `boring-tls`: handshake succeeds. lettre proceeds with the\nSMTP transaction, sending MAIL FROM, RCPT TO, message body, and any\nconfigured SMTP AUTH credentials to the attacker.\nSymmetric inverse PoC (proves the inversion, not just a missing check):\nconfigure `.dangerous_accept_invalid_hostnames(true)` and try to connect\nto a server whose cert SAN matches the connect domain. With the bug,\nthe handshake *fails* because lettre passes `true` to `verify_hostname`\nand boring rejects... actually wait, it succeeds (SAN matches). Better\ninverse demonstration: connect to a server whose cert SAN matches the\nconnect domain with `accept_invalid_hostnames=true`, then connect to a\nmismatched-SAN server with the same flag \u2014 the latter is rejected,\nproving the flag is inverted (the user opted into accepting any name,\nyet lettre enforces strict verification).\nA reproducer cargo project can be produced on request.\n\n### Impact\nWho is impacted: any lettre user who\n  1. enables the `boring-tls` feature, AND\n  2. relies on default-strict hostname verification\n     (i.e. does NOT call `.dangerous_accept_invalid_hostnames(true)`).\nThis is the entire \"I want strict TLS\" population on `boring-tls`. They\nget the opposite of what they asked for: a TLS handshake that ignores\nhostname mismatch.\nExploitation: an attacker on the network path between the lettre client\nand the target SMTP server, holding any chain-valid TLS certificate\n(e.g. a free Let\u0027s Encrypt cert for a domain the attacker owns), can\npresent that certificate when the lettre client connects to the intended\nMX. boring accepts the handshake, lettre proceeds, and the attacker\ngains read/write access to:\n  * SMTP envelope (MAIL FROM, RCPT TO)\n  * Message bodies, attachments, headers\n  * Any SMTP AUTH credentials (PLAIN, LOGIN, CRAM-MD5, etc.)\n  * Any DKIM signatures and DMARC alignment downstream depends on\n    can be inspected and selectively dropped\nConfidentiality and integrity impact: High. Availability impact: None\ndirect (the attacker can choose to forward or drop, but the bug itself\ndoes not deny service).\nCloudflare\u0027s email-fwdr independently identified and mitigated this\ndownstream by promoting a previously-metric-only post-handshake SAN\ncheck to a hard error (fix landed 2026-05-12). Because we\u0027re mitigated\ndownstream, we are not on a publication clock; we are reporting so the\nupstream fix can ship and other lettre+boring-tls deployments can stop\nrelying on per-caller workarounds. Happy to coordinate on embargo\ntiming.\nAffected versions: every released lettre version with `boring-tls`\nsupport, from v0.10.1 (PR #797, commit 985fa7e) through v0.11.21\n(latest). No prior advisory or fix.\nSuggested fix: two-line negation of the flag at the boring call sites\n(see Details). Patch is ready locally and can be attached to a private\ncollaboration fork.",
  "id": "GHSA-4pj9-g833-qx53",
  "modified": "2026-07-28T14:29:10Z",
  "published": "2026-07-28T14:29:10Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/lettre/lettre/security/advisories/GHSA-4pj9-g833-qx53"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-46428"
    },
    {
      "type": "WEB",
      "url": "https://github.com/lettre/lettre/commit/f5efffc88360dbdbfcef80f465e42d5bce68ca35"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/lettre/lettre"
    },
    {
      "type": "WEB",
      "url": "https://github.com/lettre/lettre/releases/tag/v0.11.22"
    },
    {
      "type": "WEB",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0141.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "lettre has TLS hostname verification disabled when using Boring TLS backend"
}

GHSA-4PQJ-5GG5-44JH

Vulnerability from github – Published: 2022-05-24 17:09 – Updated: 2024-04-04 02:48
VLAI
Details

An issue was discovered in openfortivpn 1.11.0 when used with OpenSSL before 1.0.2. tunnel.c mishandles certificate validation because hostname comparisons do not consider '\0' characters, as demonstrated by a good.example.com\x00evil.example.com attack.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2020-7043"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2020-02-27T18:15:00Z",
    "severity": "CRITICAL"
  },
  "details": "An issue was discovered in openfortivpn 1.11.0 when used with OpenSSL before 1.0.2. tunnel.c mishandles certificate validation because hostname comparisons do not consider \u0026#39;\\0\u0026#39; characters, as demonstrated by a good.example.com\\x00evil.example.com attack.",
  "id": "GHSA-4pqj-5gg5-44jh",
  "modified": "2024-04-04T02:48:25Z",
  "published": "2022-05-24T17:09:52Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-7043"
    },
    {
      "type": "WEB",
      "url": "https://github.com/adrienverge/openfortivpn/issues/536"
    },
    {
      "type": "WEB",
      "url": "https://github.com/adrienverge/openfortivpn/commit/6328a070ddaab16faaf008cb9a8a62439c30f2a8"
    },
    {
      "type": "WEB",
      "url": "https://github.com/adrienverge/openfortivpn/commit/cd9368c6a1b4ef91d77bb3fdbe2e5bc34aa6f4c4"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CKNKSGBVYGRRVRLFEFBEKUEJYJR5LWOF"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FF6HYIBREQGATRM5COF57MRQWKOKCWZ3"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SRVVNXCNTNMPCIAZIVR4FAGYCSU53FNA"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/CKNKSGBVYGRRVRLFEFBEKUEJYJR5LWOF"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FF6HYIBREQGATRM5COF57MRQWKOKCWZ3"
    },
    {
      "type": "WEB",
      "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/SRVVNXCNTNMPCIAZIVR4FAGYCSU53FNA"
    },
    {
      "type": "WEB",
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00009.html"
    },
    {
      "type": "WEB",
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00011.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-4PV6-Q257-8Q33

Vulnerability from github – Published: 2023-04-11 18:30 – Updated: 2024-04-04 03:24
VLAI
Details

An improper certificate validation vulnerability [CWE-295] in FortiAnalyzer and FortiManager 7.2.0 through 7.2.1, 7.0.0 through 7.0.5, 6.4.8 through 6.4.10 may allow a remote and unauthenticated attacker to perform a Man-in-the-Middle attack on the communication channel between the device and the remote FortiGuard server hosting outbreakalert ressources.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2023-22642"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2023-04-11T17:15:00Z",
    "severity": "HIGH"
  },
  "details": "An improper certificate validation vulnerability [CWE-295] in FortiAnalyzer and FortiManager 7.2.0 through 7.2.1, 7.0.0 through 7.0.5, 6.4.8 through 6.4.10 may allow a remote and unauthenticated attacker to perform a Man-in-the-Middle attack on the communication channel between the device and the remote FortiGuard server hosting outbreakalert ressources.",
  "id": "GHSA-4pv6-q257-8q33",
  "modified": "2024-04-04T03:24:40Z",
  "published": "2023-04-11T18:30:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-22642"
    },
    {
      "type": "WEB",
      "url": "https://fortiguard.com/psirt/FG-IR-22-502"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

GHSA-4Q88-82VM-7283

Vulnerability from github – Published: 2026-07-06 12:31 – Updated: 2026-07-06 12:31
VLAI
Details

Improper certificate validation vulnerability in B&R Industrial Automation GmbH APROL.

This issue affects APROL: before R 4.4-01P5.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-6900"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-06T11:16:31Z",
    "severity": "CRITICAL"
  },
  "details": "Improper certificate validation vulnerability in B\u0026R Industrial Automation GmbH APROL.\n\nThis issue affects APROL: before R 4.4-01P5.",
  "id": "GHSA-4q88-82vm-7283",
  "modified": "2026-07-06T12:31:31Z",
  "published": "2026-07-06T12:31:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6900"
    },
    {
      "type": "WEB",
      "url": "https://br-cws-assets.de-fra-1.linodeobjects.com/SA26P011-661853b7.pdf"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

GHSA-4QMX-9M2V-R9QW

Vulnerability from github – Published: 2022-05-24 19:15 – Updated: 2022-05-24 19:15
VLAI
Details

IBM Security Verify Bridge 1.0.5.0 could allow a user to obtain sensitive information due to improper certificate validation. IBM X-Force ID: 208155.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2021-38864"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2021-09-23T17:15:00Z",
    "severity": "HIGH"
  },
  "details": "IBM Security Verify Bridge 1.0.5.0 could allow a user to obtain sensitive information due to improper certificate validation. IBM X-Force ID: 208155.",
  "id": "GHSA-4qmx-9m2v-r9qw",
  "modified": "2022-05-24T19:15:30Z",
  "published": "2022-05-24T19:15:30Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-38864"
    },
    {
      "type": "WEB",
      "url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/208155"
    },
    {
      "type": "WEB",
      "url": "https://www.ibm.com/support/pages/node/6491651"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

Mitigation
Architecture and Design Implementation

Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.

Mitigation
Implementation

If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the hostname.

CAPEC-459: Creating a Rogue Certification Authority Certificate

An adversary exploits a weakness resulting from using a hashing algorithm with weak collision resistance to generate certificate signing requests (CSR) that contain collision blocks in their "to be signed" parts. The adversary submits one CSR to be signed by a trusted certificate authority then uses the signed blob to make a second certificate appear signed by said certificate authority. Due to the hash collision, both certificates, though different, hash to the same value and so the signed blob works just as well in the second certificate. The net effect is that the adversary's second X.509 certificate, which the Certification Authority has never seen, is now signed and validated by that Certification Authority.

CAPEC-475: Signature Spoofing by Improper Validation

An adversary exploits a cryptographic weakness in the signature verification algorithm implementation to generate a valid signature without knowing the key.