Identity spoofing via unbound ActivityPub signatures
Published Sep 13, 2026 · Updated Sep 13, 2026
Identity spoofing in Forgejo 13.0.0 through 16.0.4 allows remote attackers to attribute ActivityPub activities to arbitrary actors. The request verifier validates an HTTP Signature without binding its key to the actor named by inbox handlers, and it does not recompute the signed Digest over the received body. Exploitation requires federation to be enabled and a valid attacker-controlled actor keypair; it permits false attribution but not account takeover or content modification.
Summary
What happened
Identity spoofing in Forgejo 13.0.0 through 16.0.4 allows remote attackers to attribute ActivityPub activities to arbitrary actors. The request verifier validates an HTTP Signature without binding its key to the actor named by inbox handlers, and it does not recompute the signed Digest over the received body. Exploitation requires federation to be enabled and a valid attacker-controlled actor keypair; it permits false attribution but not account takeover or content modification.
The record
- CVE
- CVE-2026-90679
- Published
- Sep 13, 2026
- Updated
- Sep 13, 2026
- Vendor
- Forgejo
- Product
- Forgejo
- Classifications
- T1656
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 13, 2026CVE publishedPublication date reported by the CVE source.
- Sep 13, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=13.0.0 <=16.0.4
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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