Improper Output Neutralization for Logs in Zulip Server - #VU151558
Published: September 22, 2026
Vulnerability identifier: #VU151558
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-117
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to forge or obscure log entries.
The vulnerability exists due to improper output neutralization for logs in the /report/csp_violations endpoint when processing crafted CSP violation reports. A remote attacker can submit a crafted report containing control characters to forge or obscure log entries.
The endpoint is unauthenticated.
Affected software
Zulip Server
Remediation
Install security update from vendor's website.
Zulip Server - update to 12.3