CVE-2026-34720

BRIEFING NOTE: CVE-2026-34720 Zammad, an open-source web-based helpdesk and customer support system, contains an authentication bypass vulnerability in its Single Sign-On (SSO) mechanism affecting versions prior to 7.0.1 and 6.5.4. The flaw stems from insufficient validation of SSO proxy headers, allowing attackers to bypass authentication controls by spoofing trusted gateway requests. This vulnerability has been remediated in the patched versions listed above. The vulnerability presents a medium-severity risk with a CVSS score of 4.3. It requires network access and low privileges to exploit, with low attack complexity, but involves no user interaction. The impact is limited to confidentiality breaches through unauthorized access to information, with no integrity or availability effects anticipated. The modest EPSS score of 0.00016 indicates relatively low probability of exploitation in the wild compared to other known vulnerabilities. There is currently no evidence of active exploitation or public exploit code availability. The vulnerability does not appear on CISA's Known Exploited Vulnerabilities catalog and remains classified as inactive on exploit tracking lists. Community attention is minimal, suggesting this remains a low-priority threat requiring standard patching practices rather than emergency remediation.