CVE-2026-12329 | Memory safety bug fixed in Thunderbird ESR 140.12

Memory safety bug fixed in Thunderbird ESR 140.12. This vulnerability was fixed in Firefox ESR 140.12 and Thunderbird 140.12.

Published: 2026-06-16 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-12329 is rated Low Risk (26.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.25%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-12329

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-17 — 0.25% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-12329

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2026-12329

GitHub Security Advisory for CVE-2026-12329

GHSA-2g6w-7hp8-fv93 · Severity: medium — Memory safety bug fixed in Firefox ESR 140.12. This vulnerability was fixed in Firefox ESR 140.12.

OS Trackers for CVE-2026-12329

vendor priority summary link
debian not yet assigned CVE-2026-12329 not yet assigned priority: Debian including 2 source packages (firefox-esr, thunderbird), 10 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 10. https://security-tracker.debian.org/tracker/CVE-2026-12329
suse critical — https://www.suse.com/security/cve/CVE-2026-12329/
ubuntu medium CVE-2026-12329 medium priority: Ubuntu including 1 source packages (thunderbird), 5 status rows across 5 suites (jammy, noble, questing, resolute, upstream): needs-triage 5. https://ubuntu.com/security/CVE-2026-12329

Affected software / configurations for CVE-2026-12329

Vendor Product Version Raw CPE
mozilla firefox >= 140.0, < 140.12.0 cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
mozilla thunderbird >= 140.0, < 140.12.0 cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*

References for CVE-2026-12329

cvelogic Threat Intelligence