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Vulnerabilities

Vulnerability · CVE-2026-8958

Information disclosure, sandbox escape in the Security: Process Sandboxing component.

Published May 19, 2026 · catalog updated Oct 14, 2026 · Information disclosure, sandbox escape

Check if you run it

No confirmed exploitation is on record for CVE-2026-8958. EPSS is 0.44%. Act only if a listed version of Information disclosure, sandbox escape is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Information disclosure, sandbox escape).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.6
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.44%
Remediation
Advisory link
Affected products
cpe mozilla/firefox · cpe mozilla/thunderbird

Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

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.

  • cpe mozilla/firefoxversion unspecified
  • cpe mozilla/thunderbirdversion unspecified

How to fix CVE-2026-8958

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-2026-8958. EPSS is 0.44%. Act only if a listed version of Information disclosure, sandbox escape is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-668: Exposure of Resource to Wrong Sphere; CWE-693: Protection Mechanism Failure. EPSS 0.44%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

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. May 19, 2026 · NIST NVD

    Detected

    Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

  2. Oct 14, 2026 · NIST NVD

    Updated

    Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

Sources

  • CVE.orgVulnerability recordCVE-2026-8958

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-8958

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-8958

    Information disclosure, sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

    nvd.nist.gov

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.