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

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