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Vulnerabilities

Vulnerability · CVE-2026-109783

Mitigation bypass in the File Handling component.

Published Oct 13, 2026 · catalog updated Oct 15, 2026 · Mitigation bypass in the

Check if you run it

No confirmed exploitation is on record for CVE-2026-109783. EPSS is 0.16%. Act only if a listed version of Mitigation bypass in the is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Mitigation bypass in the).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Unknown—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.16%
Remediation
Advisory link
Affected products
Debian:12 firefox-esr · Debian:13 firefox-esr · Debian:14 firefox-esr

Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox ESR 153.5 and Thunderbird 153.5.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Debian:12 firefox-esr0 → 153.5.0esr-1~deb12u1
  • Debian:13 firefox-esr0 → 153.5.0esr-1~deb13u1
  • Debian:14 firefox-esr128.13.0esr-1, 128.14.0esr-1, 128.14.0esr-1~deb11u1

How to fix CVE-2026-109783

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-109783. EPSS is 0.16%. Act only if a listed version of Mitigation bypass in the is installed.

Which versions are affected?

Compare what you have installed with 0 → 153.5.0esr-1~deb12u1, 0 → 153.5.0esr-1~deb13u1, 128.13.0esr-1, 128.14.0esr-1, 128.14.0esr-1~deb11u1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.16%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 13, 2026 · OpenSSF OSV / OSV Scanner

    Detected

    Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox ESR 153.5 and Thunderbird 153.5.

  2. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    firefox-esr fixed in 153.5.0esr-1~deb12u1; firefox-esr fixed in 153.5.0esr-1~deb13u1

  3. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    firefox-esr fixed in 153.5.0esr-1~deb12u1

  4. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    firefox-esr fixed in 153.5.0esr-1~deb13u1

  5. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox ESR 153.5 and Thunderbird 153.5.

Sources

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.