CVE-2026-2786
critical
CVSS v3
9.8
CVSS v4 NEW
—
VIR risk
9.8
Description
Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Predictions
Exploit likelihood
97%
Patch ETA
—
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
Mitigation details
Source: Red Hat Errata — Red Hat Inc. · View original ↗ · Open-Errata-API
Description firefox: thunderbird: Use-after-free in the JavaScript Engine component Red Hat statement Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory. CVSS v3: 6.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N) Errata / fixed releases ProductPackageAdvisoryReleased Red Hat Enterprise Linux…
Description
firefox: thunderbird: Use-after-free in the JavaScript Engine component
Red Hat statement
Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
CVSS v3: 6.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)
Errata / fixed releases
| Product | Package | Advisory | Released |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | firefox-0:140.8.0-2.el10_1 | RHSA-2026:3361 | 2026-02-25T00:00:00Z |
| Red Hat Enterprise Linux 10 | thunderbird-0:140.8.0-2.el10_1 | RHSA-2026:3517 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 10.0 Extended Update Support | firefox-0:140.8.0-2.el10_0 | RHSA-2026:3976 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 10.0 Extended Update Support | thunderbird-0:140.8.0-2.el10_0 | RHSA-2026:4260 | 2026-03-11T00:00:00Z |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | firefox-0:140.8.0-2.el7_9 | RHSA-2026:3984 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 8 | firefox-0:140.8.0-2.el8_10 | RHSA-2026:3338 | 2026-02-25T00:00:00Z |
| Red Hat Enterprise Linux 8 | thunderbird-0:140.8.0-1.el8_10 | RHSA-2026:3515 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 8.2 Advanced Update Support | firefox-0:140.8.0-2.el8_2 | RHSA-2026:3492 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 8.2 Advanced Update Support | thunderbird-0:140.8.0-1.el8_2 | RHSA-2026:4432 | 2026-03-12T00:00:00Z |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | firefox-0:140.8.0-2.el8_4 | RHSA-2026:3491 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | thunderbird-0:140.8.0-2.el8_4 | RHSA-2026:3980 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | firefox-0:140.8.0-2.el8_4 | RHSA-2026:3491 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | thunderbird-0:140.8.0-2.el8_4 | RHSA-2026:3980 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | firefox-0:140.8.0-2.el8_6 | RHSA-2026:3495 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | thunderbird-0:140.8.0-1.el8_6 | RHSA-2026:3979 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 8.6 Telecommunications Update Service | firefox-0:140.8.0-2.el8_6 | RHSA-2026:3495 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 8.6 Telecommunications Update Service | thunderbird-0:140.8.0-1.el8_6 | RHSA-2026:3979 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions | firefox-0:140.8.0-2.el8_6 | RHSA-2026:3495 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions | thunderbird-0:140.8.0-1.el8_6 | RHSA-2026:3979 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 8.8 Telecommunications Update Service | firefox-0:140.8.0-2.el8_8 | RHSA-2026:3494 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 8.8 Telecommunications Update Service | thunderbird-0:140.8.0-1.el8_8 | RHSA-2026:4022 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions | firefox-0:140.8.0-2.el8_8 | RHSA-2026:3494 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions | thunderbird-0:140.8.0-1.el8_8 | RHSA-2026:4022 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 9 | firefox-0:140.8.0-2.el9_7 | RHSA-2026:3339 | 2026-02-25T00:00:00Z |
| Red Hat Enterprise Linux 9 | thunderbird-0:140.8.0-1.el9_7 | RHSA-2026:3516 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions | firefox-0:140.8.0-2.el9_0 | RHSA-2026:3493 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions | thunderbird-0:140.8.0-1.el9_0 | RHSA-2026:3983 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions | thunderbird-0:140.8.0-1.el9_2 | RHSA-2026:3978 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions | firefox-0:140.8.0-2.el9_2 | RHSA-2026:4152 | 2026-03-10T00:00:00Z |
| Red Hat Enterprise Linux 9.4 Extended Update Support | firefox-0:140.8.0-2.el9_4 | RHSA-2026:3496 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 9.4 Extended Update Support | thunderbird-0:140.8.0-1.el9_4 | RHSA-2026:3981 | 2026-03-09T00:00:00Z |
| Red Hat Enterprise Linux 9.6 Extended Update Support | firefox-0:140.8.0-2.el9_6 | RHSA-2026:3497 | 2026-03-02T00:00:00Z |
| Red Hat Enterprise Linux 9.6 Extended Update Support | thunderbird-0:140.8.0-1.el9_6 | RHSA-2026:3982 | 2026-03-09T00:00:00Z |
Package state
| Product | Package | State |
|---|---|---|
| Red Hat Enterprise Linux 10 | rhel10/firefox-flatpak | Affected |
| Red Hat Enterprise Linux 10 | rhel10/thunderbird-flatpak | Affected |
| Red Hat Enterprise Linux 6 | firefox | Out of support scope |
| Red Hat Enterprise Linux 6 | thunderbird | Out of support scope |
| Red Hat Enterprise Linux 7 | thunderbird | Out of support scope |
Apply commands
Apply RHSA-2026:3361 for Red Hat Enterprise Linux 10
yum update -y firefox
# or:
dnf upgrade -y firefoxAffected
| Vendor | Product | Version |
|---|---|---|
| redhat | Red Hat Enterprise Linux 10 | Affected |
| redhat | Red Hat Enterprise Linux 10 | Affected |
OS impact
SUSE Affected 1 release
| Version | Status | Fixed in |
|---|---|---|
| — | Affected | — |
AlmaLinux Fixed 2 releases
| Version | Status | Fixed in |
|---|---|---|
| 9 | Fixed | firefox-x11-140.8.0-2.el9_7.alma.1.x86_64.rpm |
| 8 | Fixed | firefox-140.8.0-2.el8_10.alma.1.x86_64.rpm |
Debian Fixed 5 releases
| Version | Status | Fixed in |
|---|---|---|
| trixie | Fixed | 140.8.0esr-1~deb13u1 |
| sid | Fixed | 148.0-1 |
| forky | Fixed | 140.8.0esr-1 |
| bullseye | Fixed | 140.8.0esr-1~deb11u1 |
| bookworm | Fixed | 140.8.0esr-1~deb12u1 |
Red Hat Fixed 2 releases
| Version | Status | Fixed in |
|---|---|---|
| 9 | Fixed | — |
| 8 | Fixed | — |
Rocky Linux Fixed 2 releases
| Version | Status | Fixed in |
|---|---|---|
| 9 | Fixed | — |
| 8 | Fixed | — |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| mozilla | firefox | {"endExcluding":"140.8.0"} | 140.8.0 |
| mozilla | thunderbird | {"endExcluding":"140.8.0"} | 140.8.0 |
References
- https://errata.rockylinux.org/RLSA-2026:3515
- https://errata.rockylinux.org/RLSA-2026:3338
- https://access.redhat.com/errata/RHSA-2026:3339
- https://access.redhat.com/errata/RHSA-2026:3516
- https://bugzilla.mozilla.org/show_bug.cgi?id=2013612
- https://www.mozilla.org/security/advisories/mfsa2026-13/
- https://www.mozilla.org/security/advisories/mfsa2026-15/
- https://www.mozilla.org/security/advisories/mfsa2026-16/
- https://www.mozilla.org/security/advisories/mfsa2026-17/
- https://security-tracker.debian.org/tracker/CVE-2026-2786
- https://errata.rockylinux.org/RLSA-2026:3516
- https://www.suse.com/security/cve/CVE-2026-2786.html
- https://errata.rockylinux.org/RLSA-2026:3339
- https://access.redhat.com/errata/RHSA-2026:3338
- https://bugzilla.redhat.com/2440219
- https://bugzilla.redhat.com/2442284
- https://bugzilla.redhat.com/2442287
- https://bugzilla.redhat.com/2442288
- https://bugzilla.redhat.com/2442290
- https://bugzilla.redhat.com/2442291
- https://bugzilla.redhat.com/2442292
- https://bugzilla.redhat.com/2442294
- https://bugzilla.redhat.com/2442295
- https://bugzilla.redhat.com/2442297
- https://bugzilla.redhat.com/2442298
CWEs
CWE-416
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.