Vulnerability · Published Oct 13, 2026 · Assigned by mozilla
CVE-2026-110249Denial-of-service in the Exchange email component
High 8.6
In plain English
A high-severity uncontrolled resource consumption in Thunderbird from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 8% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)8.6High
Exploit odds (30 days)0.2%top 92.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | thunderbird | 1:153.5.1esr-1~deb12u1 | DEBIAN-CVE-2026-110249 |
| Debian:13 | thunderbird | 1:153.5.1esr-1~deb13u1 | DEBIAN-CVE-2026-110249 |
| Debian:14 | thunderbird | 1:153.5.0esr-1 | DEBIAN-CVE-2026-110249 |
| Ubuntu:22.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-110249 |
| Ubuntu:24.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-110249 |
| Ubuntu:26.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-110249 |
| Ubuntu:26.10 | thunderbird | no fix listed | UBUNTU-CVE-2026-110249 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Thunderbird | see references |
Weakness: CWE-400 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H