{"api_version":"1","generated_at":"2026-09-05T03:55:10+00:00","cve":"CVE-2026-52767","urls":{"html":"https://cve.report/CVE-2026-52767","api":"https://cve.report/api/cve/CVE-2026-52767.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-52767","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-52767"},"summary":{"title":"YesWiki: Unauthenticated ActivityPub Signature-Verification Bypass via `!openssl_verify(...)` accepting `int(-1)`","description":"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.","state":"PUBLISHED","assigner":"GitHub_M","published_at":"2026-09-05 00:17:19","updated_at":"2026-09-05 00:17:19"},"problem_types":["CWE-347","CWE-347 CWE-347: Improper Verification of Cryptographic Signature"],"metrics":[{"version":"3.1","source":"security-advisories@github.com","type":"Secondary","score":"8.2","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L","baseScore":8.2,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"LOW"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"8.2","severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L","data":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":8.2,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L","version":"3.1"}}],"references":[{"url":"https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6","name":"https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/YesWiki/yeswiki/security/advisories/GHSA-mv28-wj57-f57g","name":"https://github.com/YesWiki/yeswiki/security/advisories/GHSA-mv28-wj57-f57g","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/YesWiki/yeswiki/commit/d1795e0301e1a1078f17b4b98f56fff70de2029e","name":"https://github.com/YesWiki/yeswiki/commit/d1795e0301e1a1078f17b4b98f56fff70de2029e","refsource":"security-advisories@github.com","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-52767","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-52767","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"YesWiki","product":"yeswiki","version":"affected >= 4.6.2, < 4.6.6","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"product":"yeswiki","vendor":"YesWiki","versions":[{"status":"affected","version":">= 4.6.2, < 4.6.6"}]}],"descriptions":[{"lang":"en","value":"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."}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":8.2,"baseSeverity":"HIGH","confidentialityImpact":"NONE","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-347","description":"CWE-347: Improper Verification of Cryptographic Signature","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-09-04T23:40:39.725Z","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M"},"references":[{"name":"https://github.com/YesWiki/yeswiki/security/advisories/GHSA-mv28-wj57-f57g","tags":["x_refsource_CONFIRM"],"url":"https://github.com/YesWiki/yeswiki/security/advisories/GHSA-mv28-wj57-f57g"},{"name":"https://github.com/YesWiki/yeswiki/commit/d1795e0301e1a1078f17b4b98f56fff70de2029e","tags":["x_refsource_MISC"],"url":"https://github.com/YesWiki/yeswiki/commit/d1795e0301e1a1078f17b4b98f56fff70de2029e"},{"name":"https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6","tags":["x_refsource_MISC"],"url":"https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6"}],"source":{"advisory":"GHSA-mv28-wj57-f57g","discovery":"UNKNOWN"},"title":"YesWiki: Unauthenticated ActivityPub Signature-Verification Bypass via `!openssl_verify(...)` accepting `int(-1)`"}},"cveMetadata":{"assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","assignerShortName":"GitHub_M","cveId":"CVE-2026-52767","datePublished":"2026-09-04T23:40:39.725Z","dateReserved":"2026-06-08T17:13:43.064Z","dateUpdated":"2026-09-04T23:40:39.725Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-05 00:17:19","lastModifiedDate":"2026-09-05 00:17:19","problem_types":["CWE-347","CWE-347 CWE-347: Improper Verification of Cryptographic Signature"],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L","baseScore":8.2,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"LOW"},"exploitabilityScore":3.9,"impactScore":4.2}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"52767","Ordinal":"1","Title":"YesWiki: Unauthenticated ActivityPub Signature-Verification Bypa","CVE":"CVE-2026-52767","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"52767","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"YesWiki: Unauthenticated ActivityPub Signature-Verification Bypa"}]}}}