Vulnerability in Mozilla Thunderbird

[ Description ]Official description

A malicious, compromised, or MITM-controlled Exchange server can return a single well-formed SOAP response containing an element with enough attributes to keep Thunderbird's main thread CPU-bound for seconds to hours. This vulnerability was fixed in Thunderbird 158 and Thunderbird 153.5.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• CERT-FR14 Oct 2026CERTFR-2026-AVI-1305

  Multiple vulnerabilities in Mozilla products Translated from French

  Multiple vulnerabilities have been discovered in Mozilla products. Some of them allow an attacker to cause privilege escalation, remote denial of service and a breach of data confidentiality.

  CVE-2026-109779CVE-2026-109710CVE-2026-109719+79 more CVEs
• BSI CERT-Bund13 Oct 2026WID-SEC-2026-3942

  Mozilla Firefox and Thunderbrid: Multiple vulnerabilities Translated from German

  Risk highCVE-2026-109717CVE-2026-109781CVE-2026-109710+78 more CVEs

[ References ]References

• bugzilla.mozilla.org/show_bug.cgi
• www.mozilla.org/security/advisories/mfsa2026-109
• www.mozilla.org/security/advisories/mfsa2026-110