Is CVE-2026-110249 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-110249 being exploited in the wild.

How severe is CVE-2026-110249?

Informational severity, published 13 October 2026.

Which products and versions are affected?

Mozilla Thunderbird before 158, before 153.5.

Is there a fix for CVE-2026-110249?

Yes: fixed in Thunderbird 158, Thunderbird 153.5. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-110249 attacked?

It is attacked over the network or from the adjacent network, in a software library.

Am I affected by CVE-2026-110249?

Check whether you run Mozilla Thunderbird at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-110249: Thunderbird denial-of-service in Exchange component

CVE-2026-110249 · Severity: info · Published 2026-10-13

A malicious or compromised Exchange email server can send a specially crafted response that causes Thunderbird to become unresponsive for seconds to hours. This could be exploited by attackers controlling the email server or intercepting network traffic between a user and their mail server, disrupting email access.

Technologies: Mozilla Thunderbird. Vendors: Mozilla.

Quick answers

Is CVE-2026-110249 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-110249 being exploited in the wild.
How severe is CVE-2026-110249?: Informational severity, published 13 October 2026.
Which products and versions are affected?: Mozilla Thunderbird before 158, before 153.5.
Is there a fix for CVE-2026-110249?: Yes: fixed in Thunderbird 158, Thunderbird 153.5. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-110249 attacked?: It is attacked over the network or from the adjacent network, in a software library.
Am I affected by CVE-2026-110249?: Check whether you run Mozilla Thunderbird at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: Thunderbird 158, Thunderbird 153.5

Technical details

A SOAP response element with excessive attributes causes CPU-bound processing on Thunderbird's main thread, creating a denial-of-service condition. The vulnerability requires the attacker to control or intercept the Exchange server connection. The flaw was resolved in Thunderbird 158 and 153.5.

Affected products

Mozilla Thunderbird before 158, before 153.5

Timeline

2026-10-13: disclosed

References

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