CVE-2026-52767 YesWiki: Unauthenticated ActivityPub Signature-Verification Bypass via `!openssl_verify(...)` accepting `int(-1)`

YesWiki is a wiki system written in PHP. From version 4.6.2 to before version 4.6.6, HttpSignatureService::verifySignature checks the result of PHP's opensslverify with a loose boolean negation - if !opensslverify... throw ... . PHP's opensslverify has four possible return values: 1, 0, -1, and...

PT-2026-57028

Name of the Vulnerable Software and Affected Versions YesWiki versions 4.6.2 through 4.6.5 Description An authentication bypass exists in the ActivityPub implementation due to the incorrect handling of the return value from the openssl verify function in HttpSignatureService::verifySignature. The...