What’s Vulnerable › Vulnerabilities

CVE-2026-110249: Denial-of-service in the Exchange email component

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-13 · updated 2026-10-21
• Weakness: CWE-400

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.

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2077826
• https://www.mozilla.org/security/advisories/mfsa2026-109/
• https://www.mozilla.org/security/advisories/mfsa2026-110/

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