{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "hackney_ssl"
          ],
          "packageName": "hackney",
          "packageURL": "pkg:hex/hackney",
          "product": "hackney",
          "programFiles": [
            "src/hackney_ssl.erl"
          ],
          "programRoutines": [
            {
              "name": "hackney_ssl:ssl_opts/2"
            },
            {
              "name": "hackney_ssl:merge_ssl_opts/3"
            },
            {
              "name": "hackney_ssl:partial_chain/1"
            }
          ],
          "repo": "https://github.com/benoitc/hackney",
          "vendor": "benoitc",
          "versions": [
            {
              "lessThan": "4.9.0",
              "status": "affected",
              "version": "1.24.0",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "hackney_ssl"
          ],
          "packageName": "benoitc/hackney",
          "packageURL": "pkg:github/benoitc/hackney",
          "product": "hackney",
          "programFiles": [
            "src/hackney_ssl.erl"
          ],
          "programRoutines": [
            {
              "name": "hackney_ssl:ssl_opts/2"
            },
            {
              "name": "hackney_ssl:merge_ssl_opts/3"
            },
            {
              "name": "hackney_ssl:partial_chain/1"
            }
          ],
          "repo": "https://github.com/benoitc/hackney",
          "vendor": "benoitc",
          "versions": [
            {
              "lessThan": "915eb5737e9c489d8fc22eec8cdae30e9b027be4",
              "status": "affected",
              "version": "d8a9afcf5c3849904274e2eba1df56c63d1a1a0c",
              "versionType": "git"
            }
          ]
        }
      ],
      "configurations": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eThe caller passes \u003ccode\u003ecacerts\u003c/code\u003e or \u003ccode\u003ecacertfile\u003c/code\u003e in \u003ccode\u003essl_options\u003c/code\u003e to restrict trust to a private CA, without a \u003ccode\u003epartial_chain\u003c/code\u003e of its own. Connections that use hackney\u0027s default certifi trust store are not affected.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "The caller passes `cacerts` or `cacertfile` in `ssl_options` to restrict trust to a private CA, without a `partial_chain` of its own. Connections that use hackney\u0027s default certifi trust store are not affected."
            }
          ],
          "value": "The caller passes cacerts or cacertfile in ssl_options to restrict trust to a private CA, without a partial_chain of its own. Connections that use hackney\u0027s default certifi trust store are not affected."
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:a:benoitc:hackney:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "4.9.0",
                  "versionStartIncluding": "1.24.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ],
          "operator": "AND"
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Martin Karrer"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Martin Karrer"
        },
        {
          "lang": "en",
          "type": "coordinator",
          "value": "Jonatan M\u00e4nnchen / EEF"
        }
      ],
      "dateAssigned": "2026-10-26T09:57:53.000Z",
      "datePublic": "2026-10-25T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eImproper Certificate Validation vulnerability in \u003ccode\u003ehackney_ssl\u003c/code\u003e in benoitc hackney allows an on-path attacker to impersonate a server pinned to a private certificate authority via a certificate chain that ends in a publicly trusted root. hackney adds \u003ccode\u003e{partial_chain, fun hackney_ssl:partial_chain/1}\u003c/code\u003e to every \u003ccode\u003everify_peer\u003c/code\u003e configuration. The callback returns any certificate in the peer chain whose public key matches a root in the bundled certifi store as the trust anchor, and OTP honours that callback over the configured \u003ccode\u003ecacerts\u003c/code\u003e. \u003ccode\u003ehackney_ssl:merge_ssl_opts/3\u003c/code\u003e kept the callback when the caller replaced the trust store with \u003ccode\u003ecacerts\u003c/code\u003e or \u003ccode\u003ecacertfile\u003c/code\u003e in \u003ccode\u003essl_options\u003c/code\u003e, so a connection pinned to a private CA still accepted any chain that carried a publicly trusted root.\u003c/p\u003e\n\u003cp\u003eThe hostname check still applies, so the attacker needs a publicly trusted certificate for the pinned hostname.\u003c/p\u003e\n\u003cp\u003eThis issue affects hackney: from 1.24.0 before 4.9.0.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "Improper Certificate Validation vulnerability in `hackney_ssl` in benoitc hackney allows an on-path attacker to impersonate a server pinned to a private certificate authority via a certificate chain that ends in a publicly trusted root. hackney adds `{partial_chain, fun hackney_ssl:partial_chain/1}` to every `verify_peer` configuration. The callback returns any certificate in the peer chain whose public key matches a root in the bundled certifi store as the trust anchor, and OTP honours that callback over the configured `cacerts`. `hackney_ssl:merge_ssl_opts/3` kept the callback when the caller replaced the trust store with `cacerts` or `cacertfile` in `ssl_options`, so a connection pinned to a private CA still accepted any chain that carried a publicly trusted root.\n\nThe hostname check still applies, so the attacker needs a publicly trusted certificate for the pinned hostname.\n\nThis issue affects hackney: from 1.24.0 before 4.9.0."
            }
          ],
          "value": "Improper Certificate Validation vulnerability in hackney_ssl in benoitc hackney allows an on-path attacker to impersonate a server pinned to a private certificate authority via a certificate chain that ends in a publicly trusted root. hackney adds {partial_chain, fun hackney_ssl:partial_chain/1} to every verify_peer configuration. The callback returns any certificate in the peer chain whose public key matches a root in the bundled certifi store as the trust anchor, and OTP honours that callback over the configured cacerts. hackney_ssl:merge_ssl_opts/3 kept the callback when the caller replaced the trust store with cacerts or cacertfile in ssl_options, so a connection pinned to a private CA still accepted any chain that carried a publicly trusted root.\n\nThe hostname check still applies, so the attacker needs a publicly trusted certificate for the pinned hostname.\n\nThis issue affects hackney: from 1.24.0 before 4.9.0."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-94",
          "descriptions": [
            {
              "lang": "en",
              "supportingMedia": [
                {
                  "base64": false,
                  "type": "text/html",
                  "value": "\u003cp\u003eAn attacker positioned between the client and a server pinned to a private CA, holding a publicly trusted certificate for the pinned hostname, can impersonate the server and read or modify the traffic the client sends and receives.\u003c/p\u003e"
                },
                {
                  "base64": false,
                  "type": "text/markdown",
                  "value": "An attacker positioned between the client and a server pinned to a private CA, holding a publicly trusted certificate for the pinned hostname, can impersonate the server and read or modify the traffic the client sends and receives."
                }
              ],
              "value": "An attacker positioned between the client and a server pinned to a private CA, holding a publicly trusted certificate for the pinned hostname, can impersonate the server and read or modify the traffic the client sends and receives."
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-295",
              "description": "CWE-295 Improper Certificate Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-26T13:49:29.374Z",
        "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "shortName": "EEF"
      },
      "references": [
        {
          "name": "Drop the certifi partial_chain when the caller pins cacerts or cacertfile (benoitc/hackney#978)",
          "tags": [
            "related"
          ],
          "url": "https://github.com/benoitc/hackney/pull/978"
        },
        {
          "name": "EEF CNA record for CVE-2026-115693",
          "tags": [
            "related"
          ],
          "url": "https://cna.erlef.org/cves/CVE-2026-115693.html"
        },
        {
          "name": "OSV record EEF-CVE-2026-115693",
          "tags": [
            "related"
          ],
          "url": "https://osv.dev/vulnerability/EEF-CVE-2026-115693"
        },
        {
          "name": "hackney 4.9.0 release notes",
          "tags": [
            "vendor-advisory",
            "related"
          ],
          "url": "https://github.com/benoitc/hackney/releases/tag/4.9.0"
        },
        {
          "name": "Introducing commit d8a9afc in benoitc/hackney",
          "tags": [
            "related"
          ],
          "url": "https://github.com/benoitc/hackney/commit/d8a9afcf5c3849904274e2eba1df56c63d1a1a0c"
        },
        {
          "name": "Fix commit 915eb57 in benoitc/hackney",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/benoitc/hackney/commit/915eb5737e9c489d8fc22eec8cdae30e9b027be4"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "title": "Custom cacerts or cacertfile do not restrict trust to the pinned CA in hackney",
      "workarounds": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003ePass your own \u003ccode\u003e{partial_chain, Fun}\u003c/code\u003e in \u003ccode\u003essl_options\u003c/code\u003e alongside \u003ccode\u003ecacerts\u003c/code\u003e or \u003ccode\u003ecacertfile\u003c/code\u003e. A caller-supplied \u003ccode\u003epartial_chain\u003c/code\u003e replaces hackney\u0027s in the merge, and a callback that returns \u003ccode\u003eunknown_ca\u003c/code\u003e makes OTP validate against the configured \u003ccode\u003ecacerts\u003c/code\u003e only.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "Pass your own `{partial_chain, Fun}` in `ssl_options` alongside `cacerts` or `cacertfile`. A caller-supplied `partial_chain` replaces hackney\u0027s in the merge, and a callback that returns `unknown_ca` makes OTP validate against the configured `cacerts` only."
            }
          ],
          "value": "Pass your own {partial_chain, Fun} in ssl_options alongside cacerts or cacertfile. A caller-supplied partial_chain replaces hackney\u0027s in the merge, and a callback that returns unknown_ca makes OTP validate against the configured cacerts only."
        }
      ],
      "x_technicalAnalysis": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003e\u003cstrong\u003e1. Default trust options.\u003c/strong\u003e \u003ccode\u003ehackney_ssl:check_hostname_opts/1\u003c/code\u003e builds the \u003ccode\u003everify_peer\u003c/code\u003e options for every TLS connection: the certifi \u003ccode\u003ecacerts\u003c/code\u003e, a hostname \u003ccode\u003everify_fun\u003c/code\u003e, and \u003ccode\u003e{partial_chain, fun hackney_ssl:partial_chain/1}\u003c/code\u003e. The callback walks the peer chain and returns \u003ccode\u003e{trusted_ca, Cert}\u003c/code\u003e for the first certificate whose public key matches a root in the bundled certifi store, which lets OTP accept chains that end in a cross-signed root.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2. Merge keeps the callback.\u003c/strong\u003e When the caller passes \u003ccode\u003essl_options\u003c/code\u003e, \u003ccode\u003ehackney_ssl:merge_ssl_opts/3\u003c/code\u003e merges them over the defaults with the caller\u0027s values winning per key. \u003ccode\u003ecacerts\u003c/code\u003e or \u003ccode\u003ecacertfile\u003c/code\u003e replace the trust store, and a \u003ccode\u003ecacertfile\u003c/code\u003e removes the default \u003ccode\u003ecacerts\u003c/code\u003e, but \u003ccode\u003epartial_chain\u003c/code\u003e has no counterpart in the caller\u0027s options and stays.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3. Validation.\u003c/strong\u003e OTP consults \u003ccode\u003epartial_chain\u003c/code\u003e before the configured trust store. A peer chain that carries any publicly trusted root therefore gets that root as its trust anchor, and the pinned \u003ccode\u003ecacerts\u003c/code\u003e are never consulted. Only the hostname \u003ccode\u003everify_fun\u003c/code\u003e still constrains the attacker.\u003c/p\u003e"
            },
            {
              "base64": false,
              "type": "text/markdown",
              "value": "**1. Default trust options.** `hackney_ssl:check_hostname_opts/1` builds the `verify_peer` options for every TLS connection: the certifi `cacerts`, a hostname `verify_fun`, and `{partial_chain, fun hackney_ssl:partial_chain/1}`. The callback walks the peer chain and returns `{trusted_ca, Cert}` for the first certificate whose public key matches a root in the bundled certifi store, which lets OTP accept chains that end in a cross-signed root.\n\n**2. Merge keeps the callback.** When the caller passes `ssl_options`, `hackney_ssl:merge_ssl_opts/3` merges them over the defaults with the caller\u0027s values winning per key. `cacerts` or `cacertfile` replace the trust store, and a `cacertfile` removes the default `cacerts`, but `partial_chain` has no counterpart in the caller\u0027s options and stays.\n\n**3. Validation.** OTP consults `partial_chain` before the configured trust store. A peer chain that carries any publicly trusted root therefore gets that root as its trust anchor, and the pinned `cacerts` are never consulted. Only the hostname `verify_fun` still constrains the attacker."
            }
          ],
          "value": "1. Default trust options. hackney_ssl:check_hostname_opts/1 builds the verify_peer options for every TLS connection: the certifi cacerts, a hostname verify_fun, and {partial_chain, fun hackney_ssl:partial_chain/1}. The callback walks the peer chain and returns {trusted_ca, Cert} for the first certificate whose public key matches a root in the bundled certifi store, which lets OTP accept chains that end in a cross-signed root.\n\n2. Merge keeps the callback. When the caller passes ssl_options, hackney_ssl:merge_ssl_opts/3 merges them over the defaults with the caller\u0027s values winning per key. cacerts or cacertfile replace the trust store, and a cacertfile removes the default cacerts, but partial_chain has no counterpart in the caller\u0027s options and stays.\n\n3. Validation. OTP consults partial_chain before the configured trust store. A peer chain that carries any publicly trusted root therefore gets that root as its trust anchor, and the pinned cacerts are never consulted. Only the hostname verify_fun still constrains the attacker."
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
    "assignerShortName": "EEF",
    "cveId": "CVE-2026-115693",
    "datePublished": "2026-10-26T13:49:29.374Z",
    "dateReserved": "2026-10-25T10:45:02.327Z",
    "dateUpdated": "2026-10-26T13:49:29.374Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}