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CVE-2026-8092 Mozilla CVE debrief

CVE-2026-8092 documents multiple memory safety bugs in Mozilla Firefox and Thunderbird that could enable arbitrary code execution. The vulnerability affects Firefox ESR 115.35.1, Firefox ESR 140.10.1, Firefox 150.0.1, and corresponding Thunderbird versions. Mozilla's advisory notes that some bugs showed evidence of memory corruption, and with sufficient effort, exploitation for arbitrary code execution was presumed possible. The CVSS 3.1 score of 8.1 (HIGH) reflects network attack vector, high attack complexity, no privileges required, no user interaction, and high impacts to confidentiality, integrity, and availability. The weakness enumerations include CWE-125 (Out-of-bounds Read), CWE-416 (Use After Free), and CWE-787 (Out-of-bounds Write)—all classic memory safety defect categories that frequently lead to exploitable conditions in C/C++ codebases. The fix was released on May 7, 2026, with updates to Firefox 150.0.2, Firefox ESR 140.10.2, Firefox ESR 115.35.2, Thunderbird 150.0.2, and Thunderbird 140.10.2. The CVE was modified on May 18, 2026, indicating potential updates to metadata or reference information. No known exploitation in the wild has been confirmed, and this vulnerability is not listed in CISA's Known Exploited Vulnerabilities catalog.

Vendor
Mozilla
Product
Firefox
CVSS
HIGH 8.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-07
Original CVE updated
2026-05-18
Advisory published
2026-05-07
Advisory updated
2026-05-18

Who should care

Organizations with Firefox or Thunderbird deployments, particularly those using Extended Support Release (ESR) versions in enterprise environments. Security teams responsible for endpoint protection and patch management. Users handling sensitive communications or data through Thunderbird email clients. Organizations with compliance requirements for timely vulnerability remediation given the HIGH severity rating and potential for arbitrary code execution.

Technical summary

This vulnerability encompasses multiple memory safety defects in Mozilla's Gecko engine affecting Firefox and Thunderbird. The underlying issues span several memory corruption categories: out-of-bounds read/write operations (CWE-125/CWE-787) and use-after-free conditions (CWE-416). These defects arise from improper bounds checking and lifetime management in memory allocation routines. The attack surface is primarily through malicious web content that triggers the vulnerable code paths. The high attack complexity (AC:H) in the CVSS vector suggests that successful exploitation may require specific conditions or sophisticated techniques, though the network attack vector and lack of required user interaction or privileges make this a significant remote attack risk. The fixes address the root causes through improved memory management and bounds validation.

Defensive priority

HIGH

Recommended defensive actions

  • Upgrade Firefox to version 150.0.2 or later, or ESR 140.10.2/ESR 115.35.2 or later
  • Upgrade Thunderbird to version 150.0.2 or 140.10.2 or later
  • If immediate patching is not feasible, consider disabling JavaScript or using alternative browsers for untrusted web content
  • Monitor for anomalous browser crashes or unexpected behavior that may indicate exploitation attempts
  • Review application logs for signs of memory corruption indicators or unexpected process termination
  • Prioritize patching on endpoints with access to sensitive data or elevated privilege contexts
  • Consider implementing application control policies to restrict execution of unpatched browser versions in high-risk environments

Evidence notes

Primary evidence sources include NVD CPE data confirming affected product versions, Mozilla security advisories MFSA2026-40 through MFSA2026-44, and Bugzilla bug references (though the direct bug list link is marked as broken in NVD metadata). The CVSS vector and CWE classifications are sourced from NVD secondary analysis.

Official resources

Mozilla disclosed this vulnerability on May 7, 2026, through coordinated security advisories. The disclosure includes multiple vendor advisories covering different product lines and release channels.