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Critical· 9.8official fix available

CVE-2026-52778

YesWiki, a PHP wiki system, had a flaw in its form field calculator that let attackers run arbitrary PHP code or crash the server. The bug was fixed in version 4.6.6.

publishedJun 8, 2026
last modifiedJul 23, 2026
sourcesNVD
severity · cvss
9.8
critical · how bad it is
exploitation · epss
<1%
44th percentile · chance of exploitation in 30 days
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →
auto-deletes from the system
counting…on Aug 23, 2026

An official fix is available, so this entry is kept for 30 days and then removed automatically.

01

Who is affected

YesWiki versions earlier than 4.6.6. Website owners and administrators running the wiki system.

02

Real-world impact

An attacker could crash the server or execute arbitrary PHP code, potentially taking control of the site, stealing data, or defacing content.

03

Why this severity

The CVSS score of 9.8 reflects that the vulnerability can be exploited remotely without authentication, with no user interaction, and can lead to complete compromise of confidentiality, integrity, and availability.

04

What to do about it

official fix available
recommended steps
  1. 01Upgrade YesWiki to version 4.6.6 or later.
  2. 02Verify the installation has been updated to the patched version.
  3. 03Restart the web server or clear caches to ensure the new code is loaded.

NVD-referenced vendor advisory

05

Timeline

  1. Jun 8, 2026 · Jun 8, 2026
    Published
    Disclosed and added to the National Vulnerability Database.
  2. Jul 23, 2026 · 12d ago
    Advisory updated
    The NVD record was last revised.
  3. Jul 24, 2026 · 11d ago
    Official fix available
    A vendor patch or mitigation now exists — see the remediation steps above.
06

How it’s attacked

Attack vectorNetwork (remote)
Attack complexityLow
Privileges requiredNone
User interactionNone needed
ScopeUnchanged
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
07

References & advisories

NVD advisory ↗Search advisories ↗
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →
CVE-2026-52778: YesWiki, a PHP wiki system, had a flaw in its form field calculator th · Vulnary