CVE-2026-12328

Description

Memory safety bugs present in Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151 and Thunderbird 151. 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 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.

CVSS v3.1 Score

8.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0048

Probability of exploitation

0.38%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-120 CWE-120

Affected Products

Vendor	Product	Versions
mozilla	firefox	< 115.37.0
mozilla	firefox	< 152.0
mozilla	firefox	140.0 — 140.12.0
mozilla	thunderbird	< 152.0.0
mozilla	thunderbird	140.0 — 140.12.0

References

Advisories & Patches

https://www.mozilla.org/security/advisories/mfsa2026-57/ https://www.mozilla.org/security/advisories/mfsa2026-58/ https://www.mozilla.org/security/advisories/mfsa2026-59/ https://www.mozilla.org/security/advisories/mfsa2026-60/ https://www.mozilla.org/security/advisories/mfsa2026-61/

Other References

https://bugzilla.mozilla.org/buglist.cgi?bug_id=2029402%2C2038477%2C2039726%2C2041373%2C2042268%2C2042451%2C2042782%2C2042858%2C2042929%2C2042965%2C2043213

Frequently Asked Questions

What is CVE-2026-12328? +

Memory safety bugs present in Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151 and Thunderbird 151. 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 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-12328? +

CVE-2026-12328 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0048, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-12328? +

CVE-2026-12328 affects products from mozilla, specifically: firefox, thunderbird. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-12328? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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