CWE-295
AllowedImproper Certificate Validation
Abstraction: Base · Status: Draft
The product does not validate, or incorrectly validates, a certificate.
1911 vulnerabilities reference this CWE, most recent first.
GHSA-55R6-XW9H-2C48
Vulnerability from github – Published: 2023-04-11 12:30 – Updated: 2023-04-11 12:30A vulnerability has been identified in SIMATIC IPC1047 (All versions), SIMATIC IPC1047E (All versions with maxView Storage Manager < 4.09.00.25611 on Windows), SIMATIC IPC647D (All versions), SIMATIC IPC647E (All versions with maxView Storage Manager < 4.09.00.25611 on Windows), SIMATIC IPC847D (All versions), SIMATIC IPC847E (All versions with maxView Storage Manager < 4.09.00.25611 on Windows). The Adaptec Maxview application on affected devices is using a non-unique TLS certificate across installations to protect the communication from the local browser to the local application. A local attacker may use this key to decrypt intercepted local traffic between the browser and the application and could perform a man-in-the-middle attack in order to modify data in transit.
{
"affected": [],
"aliases": [
"CVE-2023-23588"
],
"database_specific": {
"cwe_ids": [
"CWE-200",
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-04-11T10:15:00Z",
"severity": "MODERATE"
},
"details": "A vulnerability has been identified in SIMATIC IPC1047 (All versions), SIMATIC IPC1047E (All versions with maxView Storage Manager \u003c 4.09.00.25611 on Windows), SIMATIC IPC647D (All versions), SIMATIC IPC647E (All versions with maxView Storage Manager \u003c 4.09.00.25611 on Windows), SIMATIC IPC847D (All versions), SIMATIC IPC847E (All versions with maxView Storage Manager \u003c 4.09.00.25611 on Windows). The Adaptec Maxview application on affected devices is using a non-unique TLS certificate across installations to protect the communication from the local browser to the local application.\nA local attacker may use this key to decrypt intercepted local traffic between the browser and the application and could perform a man-in-the-middle attack in order to modify data in transit.",
"id": "GHSA-55r6-xw9h-2c48",
"modified": "2023-04-11T12:30:26Z",
"published": "2023-04-11T12:30:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-23588"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/pdf/ssa-511182.pdf"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-568W-37QX-3QC6
Vulnerability from github – Published: 2026-05-07 15:38 – Updated: 2026-07-20 12:32A flaw was found in gnutls. This vulnerability occurs because permitted name constraints were incorrectly ignored when previous Certificate Authorities (CAs) only had excluded name constraints. A remote attacker could exploit this to bypass critical name constraint checks during certificate validation. This bypass could lead to the acceptance of invalid certificates, potentially enabling spoofing or man-in-the-middle attacks against affected systems.
{
"affected": [],
"aliases": [
"CVE-2026-42011"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-07T15:16:09Z",
"severity": "HIGH"
},
"details": "A flaw was found in gnutls. This vulnerability occurs because permitted name constraints were incorrectly ignored when previous Certificate Authorities (CAs) only had excluded name constraints. A remote attacker could exploit this to bypass critical name constraint checks during certificate validation. This bypass could lead to the acceptance of invalid certificates, potentially enabling spoofing or man-in-the-middle attacks against affected systems.",
"id": "GHSA-568w-37qx-3qc6",
"modified": "2026-07-20T12:32:49Z",
"published": "2026-05-07T15:38:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42011"
},
{
"type": "WEB",
"url": "https://www.gnutls.org/security-new.html#GNUTLS-SA-2026-04-29-6"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2467437"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2026-42011"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:41921"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:33125"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:32962"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:30850"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:30849"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:30004"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:29197"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:26409"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:26319"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:20613"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:20612"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:20611"
},
{
"type": "WEB",
"url": "https://access.redhat.com/errata/RHSA-2026:13274"
}
],
"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"
}
]
}
GHSA-56CM-RMMQ-HQPV
Vulnerability from github – Published: 2022-05-24 22:01 – Updated: 2022-05-24 22:01In Logstash versions after 6.4.0 and before 6.8.15 and 7.12.0 a TLS certificate validation flaw was found in the monitoring feature. When specifying a trusted server CA certificate Logstash would not properly verify the certificate returned by the monitoring server. This could result in a man in the middle style attack against the Logstash monitoring data.
{
"affected": [],
"aliases": [
"CVE-2021-22138"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-05-13T18:15:00Z",
"severity": "LOW"
},
"details": "In Logstash versions after 6.4.0 and before 6.8.15 and 7.12.0 a TLS certificate validation flaw was found in the monitoring feature. When specifying a trusted server CA certificate Logstash would not properly verify the certificate returned by the monitoring server. This could result in a man in the middle style attack against the Logstash monitoring data.",
"id": "GHSA-56cm-rmmq-hqpv",
"modified": "2022-05-24T22:01:37Z",
"published": "2022-05-24T22:01:37Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-22138"
},
{
"type": "WEB",
"url": "https://discuss.elastic.co/t/elastic-stack-7-12-0-and-6-8-15-security-update/268125"
},
{
"type": "WEB",
"url": "https://security.netapp.com/advisory/ntap-20210629-0001"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-56P6-46P2-H7Q6
Vulnerability from github – Published: 2022-05-13 01:37 – Updated: 2022-05-13 01:37IBM Security Guardium 10.0, 10.0.1, 10.1, 10.1.2, 10.1.3, 10.1.4, and 10.5 does not validate, or incorrectly validates, a certificate. This weakness might allow an attacker to spoof a trusted entity by using a man-in-the-middle (MITM) techniques. IBM X-Force ID: 124740.
{
"affected": [],
"aliases": [
"CVE-2017-1265"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-12-17T16:29:00Z",
"severity": "MODERATE"
},
"details": "IBM Security Guardium 10.0, 10.0.1, 10.1, 10.1.2, 10.1.3, 10.1.4, and 10.5 does not validate, or incorrectly validates, a certificate. This weakness might allow an attacker to spoof a trusted entity by using a man-in-the-middle (MITM) techniques. IBM X-Force ID: 124740.",
"id": "GHSA-56p6-46p2-h7q6",
"modified": "2022-05-13T01:37:11Z",
"published": "2022-05-13T01:37:11Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-1265"
},
{
"type": "WEB",
"url": "https://exchange.xforce.ibmcloud.com/vulnerabilities/124740"
},
{
"type": "WEB",
"url": "https://www.ibm.com/support/docview.wss?uid=swg22014229"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/106234"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-573X-JHQH-JG36
Vulnerability from github – Published: 2019-03-25 16:16 – Updated: 2022-09-17 00:57Prior to version 0.3.0, chloride's use of net-ssh resulted in host fingerprints for previously unknown hosts getting added to the user's known_hosts file without confirmation. In version 0.3.0 this is updated so that the user's known_hosts file is not updated by chloride.
{
"affected": [
{
"package": {
"ecosystem": "RubyGems",
"name": "chloride"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.3.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2018-6517"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": true,
"github_reviewed_at": "2020-06-16T21:00:14Z",
"nvd_published_at": "2019-03-21T16:00:56Z",
"severity": "HIGH"
},
"details": "Prior to version 0.3.0, chloride\u0027s use of net-ssh resulted in host fingerprints for previously unknown hosts getting added to the user\u0027s known_hosts file without confirmation. In version 0.3.0 this is updated so that the user\u0027s known_hosts file is not updated by chloride.",
"id": "GHSA-573x-jhqh-jg36",
"modified": "2022-09-17T00:57:41Z",
"published": "2019-03-25T16:16:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-6517"
},
{
"type": "WEB",
"url": "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/chloride/CVE-2018-6517.yml"
},
{
"type": "WEB",
"url": "https://puppet.com/security/cve/CVE-2018-6517"
},
{
"type": "WEB",
"url": "https://web.archive.org/web/20201001014342/https://puppet.com/security/cve/CVE-2018-6517"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "Improper Certificate Validation in chloride"
}
GHSA-57M8-F3V5-HM5M
Vulnerability from github – Published: 2023-10-04 12:30 – Updated: 2023-11-01 17:54Withdrawn Advisory
This advisory has been withdrawn because the underlying vulnerability only concerns Red Hat's Hot Rod client, which is not in one of the GitHub Advisory Database's supported ecosystems. This link is maintained to preserve external references.
Original Description
Netty-handler has been found to no validate hostnames when using TLS in its default configuration. As a result netty-handler is vulnerable to man-in-the-middle attacks. Users would need to set the protocol to "HTTPS" in the SSLParameters of the SSLEngine to opt in to host name validation. A change in default behavior is expected in the 5.x release branch with no backport planned.
In the interim users are advised to enable host name validation in their configurations. See https://github.com/netty/netty/issues/8537 for details on the forthcoming change in default behavior.
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "io.netty:netty-handler"
},
"ranges": [
{
"events": [
{
"introduced": "4.1.0.Final"
},
{
"last_affected": "4.1.99.Final"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2023-4586"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": true,
"github_reviewed_at": "2023-10-04T20:27:04Z",
"nvd_published_at": "2023-10-04T11:15:10Z",
"severity": "MODERATE"
},
"details": "## Withdrawn Advisory\nThis advisory has been withdrawn because the underlying vulnerability only concerns Red Hat\u0027s Hot Rod client, which is not in one of the GitHub Advisory Database\u0027s [supported ecosystems](https://github.com/github/advisory-database/blob/main/README.md#supported-ecosystems). This link is maintained to preserve external references.\n\n## Original Description\nNetty-handler has been found to no validate hostnames when using TLS in its default configuration. As a result netty-handler is vulnerable to man-in-the-middle attacks. Users would need to set the protocol to \"HTTPS\" in the SSLParameters of the SSLEngine to opt in to host name validation. A change in default behavior is expected in the `5.x` release branch with no backport planned.\n\nIn the interim users are advised to enable host name validation in their configurations.\nSee https://github.com/netty/netty/issues/8537 for details on the forthcoming change in default behavior.",
"id": "GHSA-57m8-f3v5-hm5m",
"modified": "2023-11-01T17:54:21Z",
"published": "2023-10-04T12:30:14Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-4586"
},
{
"type": "WEB",
"url": "https://github.com/netty/netty/issues/8537"
},
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2023-4586"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2235564"
},
{
"type": "WEB",
"url": "https://docs.oracle.com/javase/8/docs/api/javax/net/ssl/SSLParameters.html#setEndpointIdentificationAlgorithm-java.lang.String-"
},
{
"type": "PACKAGE",
"url": "https://github.com/netty/netty"
},
{
"type": "WEB",
"url": "https://security.snyk.io/vuln/SNYK-JAVA-IONETTY-1042268"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Withdrawn Advisory: Netty-handler does not validate host names by default",
"withdrawn": "2023-11-01T17:54:21Z"
}
GHSA-58FJ-7XWC-45HQ
Vulnerability from github – Published: 2026-06-25 21:31 – Updated: 2026-06-26 21:32Un-negotiated Raw Public Key (RFC 7250) accepted in place of an X.509 certificate, bypassing chain validation. A raw public key has no chain, so ParseCertRelative() accepts it without performing any trust verification; it must therefore only be accepted when RPK was actually negotiated for that peer. The check now defaults the expected type to X.509 (per RFC 7250/8446) when no type was negotiated, comparing against the received server certificate type on the client and the selected client certificate type on the server, and rejects any mismatch, including an un-negotiated raw public key, with UNSUPPORTED_CERTIFICATE. Only affects builds with Raw Public Key support (HAVE_RPK) enabled - disabled by default in a standalone build, but included in --enable-all.
{
"affected": [],
"aliases": [
"CVE-2026-55960"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-06-25T20:17:16Z",
"severity": "HIGH"
},
"details": "Un-negotiated Raw Public Key (RFC 7250) accepted in place of an X.509 certificate, bypassing chain validation. A raw public key has no chain, so ParseCertRelative() accepts it without performing any trust verification; it must therefore only be accepted when RPK was actually negotiated for that peer. The check now defaults the expected type to X.509 (per RFC 7250/8446) when no type was negotiated, comparing against the received server certificate type on the client and the selected client certificate type on the server, and rejects any mismatch, including an un-negotiated raw public key, with UNSUPPORTED_CERTIFICATE. Only affects builds with Raw Public Key support (HAVE_RPK) enabled - disabled by default in a standalone build, but included in --enable-all.",
"id": "GHSA-58fj-7xwc-45hq",
"modified": "2026-06-26T21:32:11Z",
"published": "2026-06-25T21:31:31Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55960"
},
{
"type": "WEB",
"url": "https://github.com/wolfSSL/wolfssl/pull/10702"
},
{
"type": "WEB",
"url": "https://www.wolfssl.com/docs/security-vulnerabilities"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/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-58G4-M6H8-H97X
Vulnerability from github – Published: 2026-05-18 12:31 – Updated: 2026-05-18 12:31Dell Live Optics Windows and Personal Edition collectors contain an improper certificate validation vulnerability. A remote unauthenticated attacker could potentially exploit this vulnerability leading to loss of confidentiality and integrity.
{
"affected": [],
"aliases": [
"CVE-2026-41119"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-18T11:16:16Z",
"severity": "MODERATE"
},
"details": "Dell Live Optics Windows and Personal Edition collectors contain an improper certificate validation vulnerability. A remote unauthenticated attacker could potentially exploit this vulnerability leading to loss of confidentiality and integrity.",
"id": "GHSA-58g4-m6h8-h97x",
"modified": "2026-05-18T12:31:47Z",
"published": "2026-05-18T12:31:47Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41119"
},
{
"type": "WEB",
"url": "https://www.dell.com/support/kbdoc/en-us/000464862/dsa-2026-221-security-update-for-dell-live-optics-collector-ssl-vulnerability"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-58H4-9J5Q-GMVR
Vulnerability from github – Published: 2022-05-13 01:38 – Updated: 2022-05-13 01:38A vulnerability in the Cisco Network Plug and Play application of Cisco IOS 12.4 through 15.6 and Cisco IOS XE 3.3 through 16.4 could allow an unauthenticated, remote attacker to gain unauthorized access to sensitive data by using an invalid certificate. The vulnerability is due to insufficient certificate validation by the affected software. An attacker could exploit this vulnerability by supplying a crafted certificate to an affected device. A successful exploit could allow the attacker to conduct man-in-the-middle attacks to decrypt confidential information on user connections to the affected software. Cisco Bug IDs: CSCvc33171.
{
"affected": [],
"aliases": [
"CVE-2017-12228"
],
"database_specific": {
"cwe_ids": [
"CWE-20",
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-09-29T01:34:00Z",
"severity": "MODERATE"
},
"details": "A vulnerability in the Cisco Network Plug and Play application of Cisco IOS 12.4 through 15.6 and Cisco IOS XE 3.3 through 16.4 could allow an unauthenticated, remote attacker to gain unauthorized access to sensitive data by using an invalid certificate. The vulnerability is due to insufficient certificate validation by the affected software. An attacker could exploit this vulnerability by supplying a crafted certificate to an affected device. A successful exploit could allow the attacker to conduct man-in-the-middle attacks to decrypt confidential information on user connections to the affected software. Cisco Bug IDs: CSCvc33171.",
"id": "GHSA-58h4-9j5q-gmvr",
"modified": "2022-05-13T01:38:12Z",
"published": "2022-05-13T01:38:12Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-12228"
},
{
"type": "WEB",
"url": "https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-pnp"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/101065"
},
{
"type": "WEB",
"url": "http://www.securitytracker.com/id/1039450"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-58JG-FMCG-GCX4
Vulnerability from github – Published: 2022-05-13 01:06 – Updated: 2022-05-13 01:06Tokyo Star bank App for Android before 1.4 and Tokyo Star bank App for iOS before 1.4 do not validate SSL certificates.
{
"affected": [],
"aliases": [
"CVE-2016-1184"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-04-21T14:59:00Z",
"severity": "MODERATE"
},
"details": "Tokyo Star bank App for Android before 1.4 and Tokyo Star bank App for iOS before 1.4 do not validate SSL certificates.",
"id": "GHSA-58jg-fmcg-gcx4",
"modified": "2022-05-13T01:06:06Z",
"published": "2022-05-13T01:06:06Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2016-1184"
},
{
"type": "WEB",
"url": "http://jvn.jp/en/jp/JVN00272277/index.html"
},
{
"type": "WEB",
"url": "http://jvndb.jvn.jp/en/contents/2016/JVNDB-2016-000049.html"
},
{
"type": "WEB",
"url": "http://www.tokyostarbank.co.jp/important151222.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
Mitigation
Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
Mitigation
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.