CVE-2026-33693
Lemmy's Activitypub-Federation has SSRF via 0.0.0.0 bypass in activitypub-federation-rust v4_is_invalid()
CVSS Score
6.5
EPSS Score
0.0%
EPSS Percentile
13th
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 unauthenticated attacker controlling a remote domain can point it to 0.0.0.0, bypass the SSRF protection introduced by the fix for CVE-2025-25194 (GHSA-7723-35v7-qcxw), and reach localhost services on the target server. Version 0.7.0-beta.9 patches the issue.
| CWE | CWE-918 |
| Vendor | lemmynet |
| Product | lemmy |
| Published | Mar 27, 2026 |
| Last Updated | Mar 30, 2026 |
Stay Ahead of the Next One
Get instant alerts for lemmynet lemmy
Be the first to know when new medium vulnerabilities affecting lemmynet lemmy are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None
Affected Versions
LemmyNet / lemmy
< 0.7.0-beta.9