Chitchatter: PostMessage Handler improper authentication (CVE-2026-118129)
CVE-2026-118129 is an authentication bypass vulnerability in the Chitchatter PostMessage Handler allowing remote attackers to manipulate the parentDomain argument to perform improper authentication.
CVE search metadata
CVE search record: CVE-2026-118129. Severity: medium. CVSS: 6.3. KEV: no. Product: Chitchatter (<= f82538633813c854a81a8b2112a2f6ba17b39cbc). Brief: Chitchatter: PostMessage Handler improper authentication (CVE-2026-118129). Brief link: https://feed.craftedsignal.io/briefs/2026-10-chitchatter-auth-bypass/
Triage facts
Revision 1- Applicability
- Chitchatter (<= f82538633813c854a81a8b2112a2f6ba17b39cbc)
- Evidence
- Unknown
- Severity
- Low
- Action
- Elevated
- Sources
- 4 public sources
- Freshness
- Revision 1Oct 28, 01:35 UTC
- Vulnerabilities
- 1 CVE
- Source quality
- B3Likely
A remote improper authentication vulnerability exists in the Chitchatter application, specifically within the isConfigMessageEvent function in src/Bootstrap.tsx. The vulnerability allows an attacker to manipulate the parentDomain argument within the PostMessage Handler. Public proof-of-concept exploit code is available. The vulnerability affects versions of Chitchatter up to commit f82538633813c854a81a8b2112a2f6ba17b39cbc. A fix has been released in commit e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688.
Impact
Successful exploitation allows remote attackers to bypass authentication mechanisms within the Chitchatter application via the PostMessage interface.
Recommendation
- Identify all instances of Chitchatter in the environment.
- Apply the patch provided in commit e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688 immediately.
- Monitor for anomalous postMessage activity originating from untrusted domains targeting the Chitchatter interface.
Immediate actions
Update Chitchatter to the version containing the fix in commit e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688
Threat Hunt
Hunt for anomalous cross-origin window.postMessage events targeting the Chitchatter application
Data: Browser developer console logs, Application-specific telemetry capturing postMessage origin and data parameters
Mitigations
Apply commit e3babb5cd83bfe3b99f1d82358ac5c1ea8e8a688
CVE-2026-118129