# CVE-2025-8405: Improper Encoding or Escaping of Output in GitLab

Status: published. Published: 2025-12-11. Updated: 2026-11-04.

GitLab has remediated a security issue in GitLab CE/EE affecting all versions from 17.1 before 18.4.6, 18.5 before 18.5.4, and 18.6 before 18.6.2 that could have allowed an authenticated user to perform unauthorized actions on behalf of other users by injecting malicious HTML into vulnerability code flow displays.

## Remediation

- fix: Upgrade to versions 18.4.6, 18.5.4, 18.6.2 or above. (source: CNA: GitLab)

## Affected products and versions

- GitLab / GitLab: ≥ 17.1; < 18.4.6 (affected, semver); ≥ 18.5; < 18.5.4 (affected, semver); ≥ 18.6; < 18.6.2 (affected, semver). Source: CNA: GitLab

## Severity and prioritization

- CVSS 3.1: 7.7 (high); CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N; source: CNA: GitLab

- CISA KEV: No listing in collected sources

- EPSS: 0.52% as of 2026-11-03; percentile 43.91%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-116

## Exploit evidence

- exploit: https://hackerone.com/reports/3270940 (CNA: GitLab)

## References

- https://gitlab.com/gitlab-org/gitlab/-/issues/558214 (CNA: GitLab; issue-tracking, permissions-required)

- https://hackerone.com/reports/3270940 (CNA: GitLab; technical-description, exploit, permissions-required)

- https://about.gitlab.com/releases/2025/12/10/patch-release-gitlab-18-6-2-released/ (CNA: GitLab)

## Provenance

- CNA: GitLab: https://www.cve.org/CVERecord?id=CVE-2025-8405; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2025-8405; retrieved 2026-11-03; source updated Not reported

Revision: c99935cb7a5745fe7405ebdb2e183566d34c874ea3ea6c2075519cb5d5ce3437

Canonical: https://y2.dev/cve/CVE-2025-8405

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

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