CVE-2026-77143: Broken Access Control in extension "Forum" (pforum)
Vulnerability summary
CVE-2026-77143 is a high (CVSS 8.8) vulnerability in typo3 extension "forum". EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 34.8% of scored vulnerabilities.
Severe, CVSS 8.8 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Timeline
- 25-08-2026PublishedVulnerability first disclosed.
- 26-08-2026Last modifiedVulnerability information updated.
Description
The frontend topic editing flow does not verify on the server side that the requesting visitor owns the topic being modified. As a result, a visitor who knows the identifier of a topic from the public forum can submit a modified update request for that topic directly and overwrite its content, without the application confirming ownership. Topic identifiers are visible in the public forum listing, and exploitation requires no privileged access or non-default configuration.
CVSS metrics
2 scores · 2 sources · 1 version- NVDNIST8.8HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS trend
Probability
0.41%
Chance of exploitation in the next 30 days
Percentile
35%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.41% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-639Authorization Bypass Through User-Controlled KeyThe system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
- CWE-862Missing AuthorizationThe product does not perform an authorization check when an actor attempts to access a resource or perform an action.
Affected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Typo31 product
- extension "forum"≥ 6.0.0, < 6.2.4 | ≥ 5.0.0, < 5.0.1 | < 4.0.4
1 vendor · 1 product
References
1 links- typo3.org/security/advisory/typo3-ext-sa-2026-021Vendor Advisory