CVE-2026-104445: YesWiki before 4.6.7 Authentication Bypass via ActivityPub Inbox Actor Spoofing

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-02 · updated 2026-10-06
Weakness: CWE-290

Description

YesWiki before 4.6.7 contains an authentication bypass vulnerability in the ActivityPub inbox that fails to bind the verified HTTP signature signer to the activity actor. Unauthenticated attackers with any ActivityPub keypair can send signed Delete or Update activities referencing a mirrored entry's sourceUrl to delete or overwrite other actors' federated entries.

Affected products

yeswiki: before 4.6.7 — fixed in 4.6.7

How to fix

Upgrade to a fixed version: yeswiki 4.6.7. Check the vendor advisory for mitigations.

References

https://github.com/YesWiki/yeswiki/security/advisories/GHSA-rm6r-grfg-4v78
https://www.vulncheck.com/advisories/yeswiki-before-4.6.7-authentication-bypass-via-activitypub-inbox-actor-spoofing

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