CVE-2026-52767High· 8.2▾ MidnightPoC availableYesWiki 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 openssl_verify() with a loose boolean negation - if (!openssl_verify(...)) { throw ..…
▾ Midnight zone — Critical, or high with PoC / in-the-wild
impact 45.1 · likelihood 0 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake.
Exploit-prediction probability, daily snapshots since Sep 5.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.2%
Last analysed / modified upstream
Exploit / PoC code exists
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 openssl_verify() with a loose boolean negation - if (!openssl_verify(...)) { throw ... }. PHP's openssl_verify has four possible return values: 1, 0, -1, and "false". The -1 row is the bypass: PHP's truthiness rules make -1 a truthy value, so !(-1) === false, the throw is skipped, and the controller proceeds to processActivity(). Any condition that makes OpenSSL's EVP_VerifyFinal() return -1 triggers the bypass. The reachable consequence is the controller silently treats a failed verification as success and processes the attacker's payload. This issue has been patched in version 4.6.6.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Affected packages:
yeswiki/yeswiki >= 4.6.2, < 4.6.6Patched in:
yeswiki/yeswiki 4.6.6Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-52762High· 7.1YesWiki is a wiki system written in PHP
CVE-2026-52766Critical· 9.1YesWiki is a wiki system written in PHP
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CVE-2026-52770High· 7.5YesWiki is a wiki system written in PHP
CVE-2026-52772Medium· 5.5YesWiki is a wiki system written in PHP
CVE-2026-52773Medium· 6.1YesWiki is a wiki system written in PHP