Description
Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
Published: 2026-05-19
Score: 8.8 High
EPSS: < 1% Very Low
KEV: No
Impact: Remote Code Execution
Action: Patch Now
AI Analysis

Impact

Memory safety bugs were discovered in Thunderbird 140.10 and Thunderbird 150. The defects produced evidence of memory corruption and could, with sufficient effort, allow arbitrary code execution. The flaw was addressed by applying updates to Thunderbird 151 and 140.11, and the same fixes were also released for Firefox 151, Firefox ESR 115.36, and Firefox ESR 140.11.

Affected Systems

Mozilla Thunderbird 140.10 and Thunderbird 150 are affected. The vulnerability was remediated in Thunderbird 151 and Thunderbird 140.11. The same memory safety issues were addressed concurrently in Firefox 151, Firefox ESR 115.36, and Firefox ESR 140.11. Consequently, any system running the pre‑2019 Thunderbird or Firefox releases matching the affected versions should upgrade accordingly.

Risk and Exploitability

The EPSS score is reported as less than 1%, indicating a low but non‑zero exploitation probability, and the weakness is not listed in the CISA KEV catalog. The CVSS score of 8.8 indicates high severity. The attack vector is not specified; it is inferred that the exploitation could arise from processing untrusted content, whether locally or remotely. Due to the lack of publicly reported exploitation, the risk assessment relies solely on the described vulnerability features.

Generated by OpenCVE AI on October 23, 2026 at 01:11 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Update Mozilla Thunderbird to version 151 or newer, or to the newer supported version 140.11, to apply the memory safety fixes.
  • Apply the same update to Mozilla Firefox, installing version 151, Firefox ESR 115.36, or Firefox ESR 140.11.
  • Restart all affected Thunderbird and Firefox instances after the update to ensure the new binaries are running.
  • If an upgrade cannot be performed immediately, exposure by disabling add‑ons or features that load untrusted external content until a patched version is available.

Generated by OpenCVE AI on October 23, 2026 at 01:11 UTC.

Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4592-1 firefox-esr security update
Debian DLA Debian DLA DLA-4594-1 thunderbird security update
Debian DSA Debian DSA DSA-6283-1 firefox-esr security update
Debian DSA Debian DSA DSA-6288-1 thunderbird security update
References
Link Providers
https://access.redhat.com/errata/RHSA-2026:21378 cve-icon
https://access.redhat.com/errata/RHSA-2026:21380 cve-icon
https://access.redhat.com/errata/RHSA-2026:21381 cve-icon
https://access.redhat.com/errata/RHSA-2026:21382 cve-icon
https://access.redhat.com/errata/RHSA-2026:22325 cve-icon
https://access.redhat.com/errata/RHSA-2026:22643 cve-icon
https://access.redhat.com/errata/RHSA-2026:26174 cve-icon
https://access.redhat.com/errata/RHSA-2026:26268 cve-icon
https://access.redhat.com/errata/RHSA-2026:26269 cve-icon
https://access.redhat.com/errata/RHSA-2026:26270 cve-icon
https://access.redhat.com/errata/RHSA-2026:26491 cve-icon
https://access.redhat.com/errata/RHSA-2026:26492 cve-icon
https://access.redhat.com/errata/RHSA-2026:26493 cve-icon
https://access.redhat.com/errata/RHSA-2026:26521 cve-icon
https://access.redhat.com/errata/RHSA-2026:26536 cve-icon
https://access.redhat.com/errata/RHSA-2026:26539 cve-icon
https://access.redhat.com/errata/RHSA-2026:26551 cve-icon
https://access.redhat.com/errata/RHSA-2026:26606 cve-icon
https://access.redhat.com/errata/RHSA-2026:26629 cve-icon
https://access.redhat.com/errata/RHSA-2026:26630 cve-icon
https://access.redhat.com/errata/RHSA-2026:27715 cve-icon
https://access.redhat.com/security/cve/CVE-2026-8975 cve-icon
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1860195%2C2029325%2C2029429%2C2029910%2C2035915%2C2038678%2C2038669 cve-icon cve-icon
https://bugzilla.redhat.com/show_bug.cgi?id=2479840 cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-8975 cve-icon
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8975.json cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-8975 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-46/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-47/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-48/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-48/#CVE-2026-8975 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-50/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-51/ cve-icon cve-icon
History

Wed, 21 Oct 2026 14:00:00 +0000

Type Values Removed Values Added
Description Memory safety bugs present in Firefox ESR 115.35, Firefox ESR 140.10 and Firefox 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11. Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
Title Memory safety bugs fixed in Firefox ESR 115.36, Firefox ESR 140.11 and Firefox 151 Memory safety bugs fixed in Thunderbird 140.11 and Thunderbird 151

Tue, 26 May 2026 18:00:00 +0000

Type Values Removed Values Added
Description Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11. Memory safety bugs present in Firefox ESR 115.35, Firefox ESR 140.10 and Firefox 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
Title Memory safety bugs fixed in Thunderbird 140.11 and Thunderbird 151 Memory safety bugs fixed in Firefox ESR 115.36, Firefox ESR 140.11 and Firefox 151

Fri, 22 May 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-787
References
Metrics threat_severity

None

 threat_severity

Important

Thu, 21 May 2026 09:15:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

 cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Wed, 20 May 2026 14:45:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla thunderbird
CPEs cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
Vendors & Products Mozilla thunderbird

Tue, 19 May 2026 18:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-120
CWE-122

Tue, 19 May 2026 17:45:00 +0000

Type Values Removed Values Added
Description Memory safety bugs present in Firefox ESR 115.35, Firefox ESR 140.10 and Firefox 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, and Firefox ESR 140.11. Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
Title Memory safety bugs fixed in Firefox ESR 115.36, Firefox ESR 140.11 and Firefox 151 Memory safety bugs fixed in Thunderbird 140.11 and Thunderbird 151
References

Tue, 19 May 2026 16:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-119
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Tue, 19 May 2026 15:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-120
CWE-122

Tue, 19 May 2026 15:15:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla
Mozilla firefox
Vendors & Products Mozilla
Mozilla firefox

Tue, 19 May 2026 13:45:00 +0000

Type Values Removed Values Added
Description Memory safety bugs present in Firefox ESR 115.35, Firefox ESR 140.10 and Firefox 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, and Firefox ESR 140.11.
Title Memory safety bugs fixed in Firefox ESR 115.36, Firefox ESR 140.11 and Firefox 151
References

Subscriptions

Mozilla Firefox Thunderbird
cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2026-10-21T13:50:41.267Z

Reserved: 2026-05-19T12:30:23.949Z

Link: CVE-2026-8975

cve-icon Vulnrichment

Updated: 2026-07-15T02:47:59.420Z

cve-icon NVD

Status : Modified

Published: 2026-05-19T14:16:54.090

Modified: 2026-10-21T14:17:21.743

Link: CVE-2026-8975

cve-icon Redhat

Severity : Important

Publid Date: 2026-05-19T12:30:24Z

Links: CVE-2026-8975 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-10-23T01:15:14Z

Weaknesses
  • CWE-119

    Improper Restriction of Operations within the Bounds of a Memory Buffer

  • CWE-787

    Out-of-bounds Write