CVE-2026-12329
MEDIUM 5.3Memory safety bug fixed in Thunderbird ESR 140.12. This vulnerability was fixed in Firefox ESR 140.12 and Thunderbird 140.12.
No known exploitation, public exploit, or elevated probability at this time. Track for changes.
Exploitation likelihood
0.3%chance of exploitation in 30 days · 25th percentile
Impact if exploited
5.3CVSS 3.1 · MEDIUM
- ConfidentialityNone
- IntegrityNone
- AvailabilityLow
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept & exploit code
- github-search Search GitHub for public PoC repos
Test against your own equipment
curl -s https://vulnpedia.com/cve/CVE-2026-12329/poc.jsonMachine-readable PoC index for this CVE (for automation).Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-12329/poc.json
Affected
Products Firefox Thunderbird Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 10.0 Extended Update Support Red Hat Enterprise Linux 7 Extended Lifecycle Support Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.4 Extended Update Support Long Life Add On Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Red Hat Enterprise Linux 8.6 Extended Update Support Long Life Add On Red Hat Enterprise Linux 8.8 Telecommunications Update Service Red Hat Enterprise Linux 8.8 Update Services For Sap Solutions
Weakness (CWE)
- CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
- CWE-416: Use After Free
- CWE-476: NULL Pointer Dereference
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Known Affected Software Configurations
| Vendor | Product | Version range |
|---|---|---|
| Mozilla | Firefox | ≥ 140.0 and < 140.12.0 |
| Mozilla | Thunderbird | ≥ 140.0 and < 140.12.0 |
All CVSS metrics
- MEDIUM 5.3 v3.1 · ADP Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - HIGH 7.5 v3.1 · ADP Primary
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - MEDIUM 5.3 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - HIGH 7.5 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
References
Advisories
- https://www.mozilla.org/security/advisories/mfsa2026-58/
- https://www.mozilla.org/security/advisories/mfsa2026-61/
- https://access.redhat.com/errata/RHSA-2026:38506
- https://access.redhat.com/errata/RHSA-2026:36100
- https://access.redhat.com/errata/RHSA-2026:38751
- https://access.redhat.com/errata/RHSA-2026:27733
- https://access.redhat.com/errata/RHSA-2026:30846
- https://access.redhat.com/errata/RHSA-2026:27717
- https://access.redhat.com/errata/RHSA-2026:33445
- https://access.redhat.com/errata/RHSA-2026:36102
- https://access.redhat.com/errata/RHSA-2026:39428
- https://access.redhat.com/errata/RHSA-2026:37210
- https://access.redhat.com/errata/RHSA-2026:39141
- https://access.redhat.com/errata/RHSA-2026:36103
- https://access.redhat.com/errata/RHSA-2026:39142
- https://access.redhat.com/errata/RHSA-2026:36101
- https://access.redhat.com/errata/RHSA-2026:39706
- https://access.redhat.com/errata/RHSA-2026:39011
- https://access.redhat.com/errata/RHSA-2026:38753
- https://access.redhat.com/errata/RHSA-2026:37391
- https://access.redhat.com/errata/RHSA-2026:38750
- https://access.redhat.com/errata/RHSA-2026:27734
- https://access.redhat.com/errata/RHSA-2026:29940