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Fencer Vulns
medium 4.3

CVE-2026-90679 json

Forgejo 13.0.0 through 16.0.4, when "[federation] ENABLED = true" is set, has a spoofing issue that affects identity integrity but does not…

published 2026-09-13 57 d ago modified 2026-09-22 47 d ago also EUVD-2026-76944

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

Forgejo 13.0.0 through 16.0.4, when "[federation] ENABLED = true" is set, has a spoofing issue that affects identity integrity but does not allow account takeover or content modification. It does not verify that the HTTP Signature on an incoming ActivityPub activity was produced by the key belonging to the actor named in the activity body. The signature verification in routers/api/v1/activitypub/reqsignature.go validates the request signature, but the inbox activity handlers subsequently read the acting identity from the attacker-controlled JSON body without binding it to the verified signing key. Additionally, the signed Digest header is not recomputed against the received request body. A remote attacker who hosts a single valid ActivityPub actor and keypair can therefore submit signature-valid activities attributed to any actor identity they name.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-90679 updated cvss 4.3

forgejo: Forgejo: Identity spoofing via unverified ActivityPub signatures

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
54 d ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Affected products

  • Forgejo Forgejo

Classification

Weakness
  • CWE-348 Use of Less Trusted Source

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.