CVE-2026-77143Network attack vector

Unauthenticated topic overwrite via missing ownership check

Published Aug 25, 2026 · Updated Aug 26, 2026

Broken access control in TYPO3 Forum 4.0.3 and earlier, 5.0.0, and 6.0.0 through 6.2.3 allows remote attackers to overwrite public topics. The frontend topic editing handler accepts a caller-supplied public topic identifier and writes replacement content without checking server-side topic ownership. No authentication, privileged access, or non-default configuration is required, so any visitor can modify another user's displayed forum content.

CVSS severity8.8
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Broken access control in TYPO3 Forum 4.0.3 and earlier, 5.0.0, and 6.0.0 through 6.2.3 allows remote attackers to overwrite public topics. The frontend topic editing handler accepts a caller-supplied public topic identifier and writes replacement content without checking server-side topic ownership. No authentication, privileged access, or non-default configuration is required, so any visitor can modify another user's displayed forum content.

The record

CVE
CVE-2026-77143
Published
Aug 25, 2026
Updated
Aug 26, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-862, CWE-639, T1565.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8TYPO3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-862Missing Authorization
CWE-639Authorization Bypass Through User-Controlled Key
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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