Is CVE-2026-118180 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-118180 being exploited in the wild.

How severe is CVE-2026-118180?

Informational severity, published 27 October 2026.

Which products and versions are affected?

Mozilla Thunderbird before 159 (and before 153.6 in the ESR branch).

Is there a fix for CVE-2026-118180?

Yes: fixed in Thunderbird 159, Thunderbird 153.6. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-118180 attacked?

It is attacked over the network, in an operating system.

Am I affected by CVE-2026-118180?

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-2026-118180: Thunderbird Matrix homeserver URL validation bypass

CVE-2026-118180 · Severity: info · Published 2026-10-27

Thunderbird, an email and messaging client, failed to validate the homeserver address provided during Matrix account login, allowing a malicious homeserver to redirect the user's session to local files or network shares. On Windows, this could expose the user's NTLM credentials to an attacker; on other operating systems, attackers could read local files. This affects users setting up Matrix chat accounts in Thunderbird.

Technologies: Mozilla Thunderbird. Vendors: Mozilla.

Quick answers

Is CVE-2026-118180 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-118180 being exploited in the wild.
How severe is CVE-2026-118180?: Informational severity, published 27 October 2026.
Which products and versions are affected?: Mozilla Thunderbird before 159 (and before 153.6 in the ESR branch).
Is there a fix for CVE-2026-118180?: Yes: fixed in Thunderbird 159, Thunderbird 153.6. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-118180 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2026-118180?: 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 159, Thunderbird 153.6

Technical details

The vulnerability stems from insufficient validation of the homeserver URL returned in the Matrix login response. An attacker controlling or compromising the homeserver can provide a file: URL, causing subsequent Matrix requests to be sent to local filesystem paths or, on Windows, UNC network share paths. This leads to NTLM credential leakage on Windows via SMB authentication, or local file disclosure on other platforms.

Affected products

Mozilla Thunderbird before 159 (and before 153.6 in the ESR branch)

Timeline

2026-10-27: disclosed: Security advisory published

References

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