Full Report
Mozilla security advisory (AV26-1057)
Analysis Summary
# Vulnerability: Mozilla Firefox, Firefox ESR, and Thunderbird Security Updates (AV26-1057)
## CVE Details
- CVE ID: Not provided in the source. Consult the Mozilla advisories linked below for CVE assignments.
- CVSS Score: Not provided in the source.
- CWE: Not provided in the source.
## Affected Systems
- Products:
- Firefox ESR
- Firefox
- Thunderbird
- Versions:
- Firefox ESR: prior to 153.5 and prior to 115.43
- Firefox: prior to 158
- Thunderbird: prior to 153.5 and prior to 158
- Configurations: No specific configurations are identified in the source. The advisory states that Mozilla was affected as of October 13, 2026.
## Vulnerability Description
The Canadian Centre for Cyber Security (Cyber Centre) reports that Mozilla products are affected by vulnerabilities but does not describe the individual flaws. The source is a summary that points to Mozilla's per-product security advisories (MFSA 2026-106 through 2026-110). Technical details, affected components, and root causes must be taken from those advisories.
## Exploitation
- Status: Not stated in the source. Treat as unknown and check Mozilla's advisories and vendor or threat intelligence for exploitation reports.
- Complexity: Not stated in the source.
- Attack Vector: Not stated in the source. Browser and mail-client vulnerabilities are commonly reached over the network, but this should be confirmed from the Mozilla advisories.
## Impact
- Confidentiality: Not specified in the source.
- Integrity: Not specified in the source.
- Availability: Not specified in the source.
## Remediation
### Patches
- Firefox: update to version 158 or later.
- Firefox ESR: update to version 153.5 or later for the 153 branch, and to version 115.43 or later for the 115 branch.
- Thunderbird: update to version 158 or later, and to version 153.5 or later for the 153 branch.
### Workarounds
- No workarounds are provided in the source. Applying the vendor updates is the recommended mitigation.
- Until patching is complete, prioritize systems that process untrusted content or are exposed to external users, as a general precaution.
## Detection
- Indicators of compromise: None are provided in the source.
- Detection methods and tools:
- Inventory Firefox, Firefox ESR, and Thunderbird installations and compare their versions against the fixed versions above.
- Verify versions on endpoints with the About dialog in each application (Help > About Firefox / About Thunderbird) or through software management tools.
- Confirm that ESR deployments are on the correct branch (115.43+ or 153.5+) so they do not remain on an older ESR track.
## References
- Source advisory (Cyber Centre, French version): hxxps://www[.]cyber[.]gc[.]ca/fr/alertes-avis/bulletin-securite-mozilla-av26-1057
- Government of Canada: hxxps://www[.]canada[.]ca/en[.]html
- Security Vulnerabilities fixed in Firefox 158 (MFSA 2026-106): hxxps://www[.]mozilla[.]org/en-US/security/advisories/mfsa2026-106/
- Mozilla Foundation Security Advisory 2026-107 (MFSA 2026-107): hxxps://www[.]mozilla[.]org/en-US/security/advisories/mfsa2026-107/
- Security Vulnerabilities fixed in Firefox ESR 153.5 (MFSA 2026-108): hxxps://www[.]mozilla[.]org/en-US/security/advisories/mfsa2026-108/
- Security Vulnerabilities fixed in Thunderbird 158 (MFSA 2026-109): hxxps://www[.]mozilla[.]org/en-US/security/advisories/mfsa2026-109/
- Security Vulnerabilities fixed in Thunderbird 153.5 (MFSA 2026-110): hxxps://www[.]mozilla[.]org/en-US/security/advisories/mfsa2026-110/
- Mozilla Foundation Security Advisories index: hxxps://www[.]mozilla[.]org/en-US/security/advisories/