# CVE-2026-120263: Gitea OAuth2 account auto-linking takeover through the sign-up form

Status: published. Published: 2026-11-01. Updated: 2026-11-06.

When `[oauth2_client].ACCOUNT_LINKING` is set to `auto` (not the default) and registration is enabled, the link-account sign-up form looked up the existing account to link by the user name or email submitted in the form instead of the identity asserted by the OAuth2 provider. An attacker with an account on a configured OAuth2 provider could submit another user's name, link their external identity to that Gitea account and be signed in as it without its password, including as an administrator. The link persisted for later sign-ins. Automatic linking now only happens when the existing account matches the provider's email or provider-derived user name; otherwise the account password is required.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: Gitea) — https://github.com/go-gitea/gitea/pull/40121
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: Gitea) — https://github.com/go-gitea/gitea/pull/40137
- fix: gitea.dev (go): GitHub reports patched versions 28.3.0. Check the advisory for the affected release branch. (source: GitHub GHSA-8p3x-w464-4g6v) — https://github.com/go-gitea/gitea/security/advisories/GHSA-8p3x-w464-4g6v

## Affected products and versions

- Gitea / Gitea (gitea.dev): ≥ 0; < 28.3.0 (affected, semver). Source: CNA: Gitea
-  / gitea.dev (gitea.dev): <= 28.2.0 (affected, GitHub advisory range). Source: GitHub GHSA-8p3x-w464-4g6v

## Severity and prioritization

- CVSS 3.1: 9.8 (critical); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H; source: ADP: CISA-ADP

- CISA KEV: No listing in collected sources

- EPSS: 0.16% as of 2026-11-06; percentile 5.47%

- SSVC: exploitation none; automatable yes; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-287, CWE-639

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/go-gitea/gitea/security/advisories/GHSA-8p3x-w464-4g6v (CNA: Gitea; vendor-advisory)

- https://github.com/go-gitea/gitea/pull/40121 (CNA: Gitea; patch)

- https://github.com/go-gitea/gitea/pull/40137 (CNA: Gitea; patch)

- https://blog.gitea.com/release-of-28.3.0/ (CNA: Gitea; release-notes)

- https://github.com/go-gitea/gitea/releases/tag/v28.3.0 (CNA: Gitea; release-notes)

- https://blog.gitea.com/release-of-28.3.0/ (88ee5874-cf24-4952-aea0-31affedb7ff2)

- https://github.com/go-gitea/gitea/pull/40121 (88ee5874-cf24-4952-aea0-31affedb7ff2)

- https://github.com/go-gitea/gitea/pull/40137 (88ee5874-cf24-4952-aea0-31affedb7ff2)

- https://github.com/go-gitea/gitea/releases/tag/v28.3.0 (88ee5874-cf24-4952-aea0-31affedb7ff2)

- https://github.com/go-gitea/gitea/security/advisories/GHSA-8p3x-w464-4g6v (88ee5874-cf24-4952-aea0-31affedb7ff2)

- https://github.com/go-gitea/gitea/security/advisories/GHSA-8p3x-w464-4g6v (GitHub Security Advisories; advisory)

## Provenance

- CNA: Gitea: https://www.cve.org/CVERecord?id=CVE-2026-120263; retrieved 2026-11-06; source updated 2026-11-06

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-120263; retrieved 2026-11-02; source updated 2026-11-01

- GitHub Security Advisories: https://github.com/go-gitea/gitea/security/advisories/GHSA-8p3x-w464-4g6v; retrieved 2026-11-02; source updated 2026-11-01

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-120263; retrieved 2026-11-06; source updated Not reported

Revision: 004dfe86c95f977d4c43254beb61da575650eac7f53cc8cb709af89fe2605f8f

Canonical: https://y2.dev/cve/CVE-2026-120263

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