CVE-2026-6768
Published: 21 April 2026
Summary
CVE-2026-6768 is a critical-severity Authentication Bypass Using an Alternate Path or Channel (CWE-288) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Browser Session Hijacking (T1185); ranked at the 20.3th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and SI-5 (Security Alerts, Advisories, and Directives).
Deeper analysis
CVE-2026-6768 is a mitigation bypass vulnerability in the Networking: Cookies component of Mozilla Firefox and Thunderbird. Published on 2026-04-21, it carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) and is associated with CWE-288. The issue was addressed in Firefox version 150 and Thunderbird version 150.
The vulnerability enables exploitation by any unauthenticated remote attacker requiring low complexity and no user interaction. Successful attacks can result in high impacts to confidentiality, integrity, and availability, allowing attackers to bypass mitigations in cookie handling within the networking stack.
Mozilla's security advisories MFSA2026-30 and MFSA2026-33, along with Bugzilla entry 2023615, provide details on the flaw. Mitigation requires updating affected systems to Firefox 150 or Thunderbird 150.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-24109
Vulnerability details
Mitigation bypass in the Networking: Cookies component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Mitigation bypass in browser cookie handling directly enables/facilitates browser session hijacking and stealing web session cookies by circumventing security controls in the networking stack.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mandates identification, reporting, and correction of the mitigation bypass flaw in Firefox and Thunderbird's Networking: Cookies component via patching to version 150.
Requires obtaining and disseminating security advisories such as Mozilla's MFSA2026-30 and MFSA2026-33 to enable timely patching of the cookie handling vulnerability.
Vulnerability scanning detects systems running vulnerable versions of Firefox or Thunderbird affected by CVE-2026-6768.
Hardening callouts derived
Configuration rules from DISA STIG baselines that reduce the attack surface for weaknesses of the type cited by this CVE. Derived transitively via CVE→CWE→STIG over `controls_xwalks` (authoritative rows only).
Oracle Linux 8 (2 rules)
- V-248598 There must be no ".shosts" files on the OL 8 operating system. via CWE-288
- V-248827 OL 8 must not have the rsh-server package installed. via CWE-288
Oracle Linux 9 (2 rules)
- V-271757 OL 9 file systems must not contain shosts.equiv files. via CWE-288
- V-271758 OL 9 file systems must not contain .shosts files. via CWE-288
RHEL 7 (3 rules)
- V-204424 The Red Hat Enterprise Linux operating system must not allow accounts configured with blank or null passwords. via CWE-288
- V-204440 Red Hat Enterprise Linux operating systems version 7.2 or newer using Unified Extensible Firmware Interface (UEFI) must require authentication upon booting into single-user and maintenance modes. via CWE-288
- V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. via CWE-288