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VulnerabilityPublished Updated

CVE-2026-45186: thunderbird security, bug fix, and enhancement update

Affects thunderbirdSource GCVE Database

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Authoritative record:CVE-2026-45186· Low 2.9

Not known to be exploited · CVSS 2.9 Low : upgrade to 153.5.0-1.el10_2.alma.1 when convenient.

Data as of 29 Oct 2026, 14:41 UTC

CVSS 3.1 base score
2.9Low
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 153.5.0-1.el10_2.alma.1
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 10 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 29 Oct 2026.

What to do

Upgrade the AlmaLinux thunderbird package to 153.5.0-1.el10_2.alma.1.

Affected software

ProductAffectedFixed in
AlmaLinux 10thunderbirdAffected
  • <153.5.0-1.el10_2.alma.1
Fixed in
  • 153.5.0-1.el10_2.alma.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A security update fixing this vulnerability is available in Thunderbird version 153.5.0-1.el10_2.alma.1 and later. Users and administrators should apply this update promptly to remediate the denial of service issue. Refer to the Red Hat advisory and update instructions at https://access.redhat.com/articles/11258 for detailed guidance.

Description

Mozilla Thunderbird contains a vulnerability in the libexpat XML parsing library that allows denial of service via crafted XML input (CVE-2026-45186). This security issue is addressed in Thunderbird version 153.5.0-1.el10_2.alma.1 and later. The update also includes bug fixes and enhancements related to the Thunderbird ESR 153 rebase for Red Hat Enterprise Linux 10.2 Extended Update Support.

References

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