Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1336 CNY

100%
Buy Us a Coffee

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

Quick assessment

Affected
YesWiki yeswiki
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

YesWiki 是一个用 PHP 编写的 Wiki 系统。从 4.6.2 版本到 4.6.6 版本之前， 方法中使用了一个宽松的布尔取反来检查 PHP 的返回值，具体形式为 。 PHP 的 有四种可能的返回值： 、 、 和 。其中， 是漏洞绕过的关键：根据 PHP 的“真值”（truthiness）规则， 被视为真值（truthy），因此 的结果是 ，导致 语句被跳过，控制器继续执行 。任何导致 OpenSSL 的 返回 的情况都会触发这一绕过。 由此产生的实际后果是：控制器将验证失败静默地当作成功处理，并继续处理

CVSS 8.2 · High EPSS 0.02% · P6

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-52767

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
YesWiki: Unauthenticated ActivityPub Signature-Verification Bypass via `!openssl_verify(...)` accepting `int(-1)`
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
密码学签名的验证不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
YesWiki yeswiki >= 4.6.2, < 4.6.6 -

II. Public POCs for CVE-2026-52767

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
default-local-qwen3.6 · 7793 chars
Pro+ exclusive includes:
Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
Full executable POC code
Exploit chain & mitigation
POC zip download
100+ AI POC generations per month

III. Intelligence Information for CVE-2026-52767

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-52767 (1)

Vendor Advisories for CVE-2026-52767 (1)

Other References for CVE-2026-52767 (1)

Same Patch Batch · YesWiki · 2026-09-04 · 12 CVEs total

CVE-2026-52777 9.4 CRITICAL YesWiki: Authenticated PHP Object Injection in BazarImportAction via unserialize
CVE-2026-52766 9.1 CRITICAL YesWiki: Unauthenticated arbitrary page deletion via `{{erasespamedcomments}}` action
CVE-2026-52775 8.8 HIGH YesWiki Authenticated SQL Injection in ReactionManager
CVE-2026-52769 8.3 HIGH YesWiki: Unauthenticated Server-Side Request Forgery via ActivityPub `Signature.keyId`
CVE-2026-52771 8.3 HIGH YesWiki: Second-Order SQL Injection in Page Delete API via Unescaped Page Tag (`ApiControl
CVE-2026-52770 7.5 HIGH Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection') in ye
CVE-2026-52762 7.1 HIGH YesWiki: Authenticated (Admin) Server-Side Template Injection to Remote Code Execution via
CVE-2026-52763 6.5 MEDIUM YesWiki: SQL injection via the `recentchanges` action `period` argument leading to arbitra
CVE-2026-52773 6.1 MEDIUM Reflected XSS via Unescaped Archived-Revision `time` Parameter in `handlers/page/show.php`
CVE-2026-52774 6.1 MEDIUM Reflected XSS via Unescaped `id` Parameter in Bazar Widget HTML Attributes in YesWiki
CVE-2026-52772 5.5 MEDIUM YesWiki: Bazar form-field templates still apply `|raw('html')` to `field.label` / `field.h

IV. Related Vulnerabilities

Same product: yeswiki
Same vendor: YesWiki
Same weakness: CWE-347

V. Comments for CVE-2026-52767

No comments yet

Leave a comment