CVE-2026-118177: Mozilla Thunderbird · Calendar discovery accepted local file and remote network share locations
Affects Mozilla ThunderbirdSource CVE Database V5
Not known to be exploited · fixed in 153.6 : patch Mozilla Thunderbird soon.
Data as of 27 Oct 2026, 18:57 UTC
Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD
- Patch
- Available – fixed in 153.6
Exploitation evidence
Disclosed: evidence found.
CVE published 27 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
AI-suggested
This vulnerability has been fixed in Thunderbird version 159. Users and administrators should update to Thunderbird 159 or later to remediate this issue. No additional mitigation steps are required once the update is applied.
Description
When looking for calendars in a directory on a server, during account setup or when adding a new network calendar, Thunderbird accepted calendar locations pointing to other servers, local files or network shares. A malicious server, or a network attacker when the lookup used plain HTTP, could make Thunderbird subscribe to such a location. On Windows this could leak the user's NTLM credentials to an attacker-controlled host on every calendar refresh, and changes to the calendar could be written to the attacker's share or overwrite a local file. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.