SSRF in Lemmynet Lemmy
CVE-2026-33693
Lemmy is a link aggregator and forum for the fediverse. Prior to version 0.7.0-beta.9, the `v4_is_invalid()` function in `activitypub-federation-rust` (`src/utils.rs`) does not check for `Ipv4Addr::UNSPECIFIED` (0.0.0.0). An unauthenticate…
Vulnerability class: SSRF (Server-Side Request Forgery)
EPSS: 0.000 (6.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.
Affected products
- Lemmynet Lemmy — versions < 0.7.0-beta.9
Weakness classification (CWE)
Public proof-of-concept exploits
References
- https://github.com/LemmyNet/lemmy/security/advisories/GHSA-q537-8fr5-cw35 (x_refsource_CONFIRM)
- https://github.com/LemmyNet/activitypub-federation-rust/commit/4ae8532b17bc35755240b7f55d4a5b7665351599 (x_refsource_MISC)
- https://github.com/advisories/GHSA-7723-35v7-qcxw (x_refsource_MISC)
Frequently asked questions
- What is CVE-2026-33693?
- CVE-2026-33693 is a medium-severity vulnerability in Lemmynet Lemmy, classified under Server-Side Request Forgery (SSRF). CVSS score: 6.5/10. Published 2026-03-27.
- How severe is CVE-2026-33693?
- Medium severity. CVSS v3 base score is 6.5 out of 10.
- Is CVE-2026-33693 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.