Server-Side Request Forgery (SSRF) in activitypub_federation

published 2025-02-10 20 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-4082 , GHSA-7723-35v7-qcxw

cvss: 4.0; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 36%
public exploits: 0; none known

Lemmy, a link aggregator and forum for the fediverse, is vulnerable to server-side request forgery via a dependency on activitypub_federation, a framework for ActivityPub federation in Rust. This vulnerability, which is present in versions 0.6.2 and prior of activitypub_federation and versions 0.19.8 and prior of Lemmy, allows a user to bypass any predefined hardcoded URL path or security anti-Localhost mechanism and perform an arbitrary GET request to any Host, Port and URL using a Webfinger Request. As of time of publication, a fix has not been made available.

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 20 mo ago (2025-02-11)

Exploit prediction

0.42% chance of exploitation in the next 30 days, higher than 36% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	4.0	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N
GitHub	3.1	4.0	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N

Affected packages

ecosystem	package	affected	fixed in
crates.io	activitypub_federation	<=0.6.2	no fix listed

Affected products

LemmyNet lemmy

Classification

Weakness

CWE-918 Server-Side Request Forgery

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary