CVE-2026-29178: Lemmy has unauthenticated SSRF via file_type query parameter injection in image endpoint

March 4, 2026 (updated March 6, 2026)

The GET /api/v4/image/{filename} endpoint is vulnerable to unauthenticated SSRF through parameter injection in the file_type query parameter. An attacker can inject arbitrary query parameters into the internal request to pict-rs, including the proxy parameter which causes pict-rs to fetch arbitrary URLs.

References

github.com/LemmyNet/lemmy
github.com/LemmyNet/lemmy/commit/f47a03f56d1797bceab5f34b6f624c91cecd5871
github.com/LemmyNet/lemmy/security/advisories/GHSA-jvxv-2jjp-jxc3
github.com/advisories/GHSA-jvxv-2jjp-jxc3
nvd.nist.gov/vuln/detail/CVE-2026-29178

Code Behaviors & Features

Detect and mitigate CVE-2026-29178 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Dependency Scanning using SBOM also detects vulnerabilities from proprietary advisories that this site does not include. Learn more about Dependency Scanning using SBOM →