Vulnerability DatabaseCVE-2026-33693
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CVE-2026-33693
March 27, 2026
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.
Affected Packages
https://github.com/LemmyNet/activitypub-federation-rust.git (GITHUB):
Affected version(s) >=0.1.0 <0.7.0-beta.9
Fix Suggestion:
Update to version 0.7.0-beta.9
https://github.com/LemmyNet/activitypub-federation-rust.git (GITHUB):
Affected version(s) >=0.1.0 <0.7.0-beta.9
Fix Suggestion:
Update to version 0.7.0-beta.9
https://github.com/LemmyNet/activitypub-federation-rust.git (GITHUB):
Affected version(s) >=0.1.0 <0.7.0-beta.9
Fix Suggestion:
Update to version 0.7.0-beta.9
activitypub_federation (RUST):
Affected version(s) >=0.1.0 <0.7.0-beta.9
Fix Suggestion:
Update to version 0.7.0-beta.9
activitypub_federation (RUST):
Affected version(s) >=0.1.0 <0.7.0-beta.9
Fix Suggestion:
Update to version 0.7.0-beta.9
activitypub_federation (RUST):
Affected version(s) >=0.1.0 <0.7.0-beta.9
Fix Suggestion:
Update to version 0.7.0-beta.9
activitypub_federation (RUST):
Affected version(s) >=0.1.0 <0.7.0-beta.9
Fix Suggestion:
Update to version 0.7.0-beta.9
Related Resources (5)
https://github.com/LemmyNet/activitypub-federation-rust
https://nvd.nist.gov/vuln/detail/CVE-2026-33693
https://github.com/LemmyNet/activitypub-federation-rust/commit/4ae8532b17bc35755240b7f55d4a5b7665351599
https://github.com/advisories/GHSA-7723-35v7-qcxw
https://github.com/LemmyNet/lemmy/security/advisories/GHSA-q537-8fr5-cw35
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CVSS v4
Base Score:
6.9
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
LOW
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
Server-Side Request Forgery (SSRF)
CWE-918
EPSS
Base Score:
0.04