{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "HIGH",
              "attackVector": "NETWORK",
              "availabilityImpact": "HIGH",
              "baseScore": 7.5,
              "baseSeverity": "HIGH",
              "confidentialityImpact": "HIGH",
              "integrityImpact": "HIGH",
              "privilegesRequired": "LOW",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-109553",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-19T20:19:01.147709Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-19T20:19:06.039Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "packageName": "gitea.dev",
          "product": "Gitea",
          "vendor": "Gitea",
          "versions": [
            {
              "lessThanOrEqual": "28.1.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "https://github.com/DshtAnger"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "https://github.com/silverwind"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "https://github.com/wxiaoguang"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "https://github.com/bircni"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Gitea resolved the principals of an SSH certificate by searching the content of all stored public keys instead of only principal keys. When Gitea trusts a user certificate authority (`SSH_TRUSTED_USER_CA_KEYS`) and accepts arbitrary principals (`SSH_AUTHORIZED_PRINCIPALS_ALLOW=anything`), a user could register another user\u0027s public key line as their own principal, or a holder of a certificate signed by that authority could list it, and then authenticate as the owner of that key through the HTTP signature API and the built-in SSH server. Instances that do not trust a user certificate authority are not affected."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-18T18:51:31.037Z",
        "orgId": "88ee5874-cf24-4952-aea0-31affedb7ff2",
        "shortName": "Gitea"
      },
      "references": [
        {
          "name": "GitHub Security Advisory GHSA-vcp6-2qc6-gvq3",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://github.com/go-gitea/gitea/security/advisories/GHSA-vcp6-2qc6-gvq3"
        },
        {
          "name": "Fix: go-gitea/gitea pull request #39839",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/go-gitea/gitea/pull/39839"
        },
        {
          "name": "Fix backport to release/v28: go-gitea/gitea pull request #39847",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/go-gitea/gitea/pull/39847"
        },
        {
          "name": "Gitea 28.2.0 release announcement",
          "tags": [
            "release-notes"
          ],
          "url": "https://blog.gitea.com/release-of-28.2.0/"
        },
        {
          "name": "go-gitea/gitea v28.2.0 release",
          "tags": [
            "release-notes"
          ],
          "url": "https://github.com/go-gitea/gitea/releases/tag/v28.2.0"
        }
      ],
      "title": "Gitea SSH certificate principal impersonation of other users"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "88ee5874-cf24-4952-aea0-31affedb7ff2",
    "assignerShortName": "Gitea",
    "cveId": "CVE-2026-109553",
    "datePublished": "2026-10-18T18:51:31.037Z",
    "dateReserved": "2026-10-14T20:08:45.856Z",
    "dateUpdated": "2026-10-19T20:19:06.039Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}