Memory safety bugs fixed in Firefox ESR 140.7, Thunderbird ESR 140.7, Firefox 147 and Thunderbird 147
Published Jan 13, 2026
8.1
HIGHCVSS 3.1
EPSS 0.48%
Description
Memory safety bugs present in Firefox ESR 140.6, Thunderbird ESR 140.6, Firefox 146 and Thunderbird 146. 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 147, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.
Affected products
No data.
- < 140.7.0
- < 147.0
- < 140.7.0
- < 147.0
No data.
Red Hat Enterprise Linux 10
firefox-0:140.7.0-1.el10_1
Fixed · RHSA-2026:2271
Red Hat Enterprise Linux 10
thunderbird-0:140.7.0-1.el10_1
Fixed · RHSA-2026:2286
Red Hat Enterprise Linux 10.0 Extended Update Support
firefox-0:140.7.0-1.el10_0
Fixed · RHSA-2026:2271
Red Hat Enterprise Linux 10.0 Extended Update Support
thunderbird-0:140.7.0-1.el10_0
Fixed · RHSA-2026:2286
Red Hat Enterprise Linux 7 Extended Lifecycle Support
firefox-0:140.7.0-1.el7_9
Fixed · RHSA-2026:2231
Red Hat Enterprise Linux 8
firefox-0:140.7.0-1.el8_10
Fixed · RHSA-2026:0667
Red Hat Enterprise Linux 8
thunderbird-0:140.7.0-1.el8_10
Fixed · RHSA-2026:2220
Red Hat Enterprise Linux 8.2 Advanced Update Support
firefox-0:140.7.0-1.el8_2
Fixed · RHSA-2026:2074
Red Hat Enterprise Linux 8.2 Advanced Update Support
thunderbird-0:140.7.0-1.el8_2
Fixed · RHSA-2026:1471
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
firefox-0:140.7.0-1.el8_4
Fixed · RHSA-2026:2073
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
thunderbird-0:140.7.0-1.el8_4
Fixed · RHSA-2026:1461
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
firefox-0:140.7.0-1.el8_4
Fixed · RHSA-2026:2073
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
thunderbird-0:140.7.0-1.el8_4
Fixed · RHSA-2026:1461
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
firefox-0:140.7.0-1.el8_6
Fixed · RHSA-2026:2070
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
thunderbird-0:140.7.0-1.el8_6
Fixed · RHSA-2026:1487
Red Hat Enterprise Linux 8.6 Telecommunications Update Service
firefox-0:140.7.0-1.el8_6
Fixed · RHSA-2026:2070
Red Hat Enterprise Linux 8.6 Telecommunications Update Service
thunderbird-0:140.7.0-1.el8_6
Fixed · RHSA-2026:1487
Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
firefox-0:140.7.0-1.el8_6
Fixed · RHSA-2026:2070
Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
thunderbird-0:140.7.0-1.el8_6
Fixed · RHSA-2026:1487
Red Hat Enterprise Linux 8.8 Telecommunications Update Service
firefox-0:140.7.0-1.el8_8
Fixed · RHSA-2026:2069
Red Hat Enterprise Linux 8.8 Telecommunications Update Service
thunderbird-0:140.7.0-1.el8_8
Fixed · RHSA-2026:1462
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
firefox-0:140.7.0-1.el8_8
Fixed · RHSA-2026:2069
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
thunderbird-0:140.7.0-1.el8_8
Fixed · RHSA-2026:1462
Red Hat Enterprise Linux 9
firefox-0:140.7.0-1.el9_7
Fixed · RHSA-2026:0694
Red Hat Enterprise Linux 9
thunderbird-0:140.7.0-1.el9_7
Fixed · RHSA-2026:0924
Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions
firefox-0:140.7.0-1.el9_0
Fixed · RHSA-2026:2047
Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions
thunderbird-0:140.7.0-1.el9_0
Fixed · RHSA-2026:1413
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
firefox-0:140.7.0-1.el9_2
Fixed · RHSA-2026:2044
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
thunderbird-0:140.7.0-1.el9_2
Fixed · RHSA-2026:1415
Red Hat Enterprise Linux 9.4 Extended Update Support
firefox-0:140.7.0-1.el9_4
Fixed · RHSA-2026:2041
Red Hat Enterprise Linux 9.4 Extended Update Support
thunderbird-0:140.7.0-1.el9_4
Fixed · RHSA-2026:1414
Red Hat Enterprise Linux 9.6 Extended Update Support
firefox-0:140.7.0-1.el9_6
Fixed · RHSA-2026:2043
Red Hat Enterprise Linux 9.6 Extended Update Support
thunderbird-0:140.7.0-2.el9_6
Fixed · RHSA-2026:1320
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
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | firefox-0:140.7.0-1.el10_1 | Fixed | RHSA-2026:2271 |
| Red Hat Enterprise Linux 10 | thunderbird-0:140.7.0-1.el10_1 | Fixed | RHSA-2026:2286 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | firefox-0:140.7.0-1.el10_0 | Fixed | RHSA-2026:2271 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | thunderbird-0:140.7.0-1.el10_0 | Fixed | RHSA-2026:2286 |
| Red Hat Enterprise Linux 7 Extended Lifecycle Support | firefox-0:140.7.0-1.el7_9 | Fixed | RHSA-2026:2231 |
| Red Hat Enterprise Linux 8 | firefox-0:140.7.0-1.el8_10 | Fixed | RHSA-2026:0667 |
| Red Hat Enterprise Linux 8 | thunderbird-0:140.7.0-1.el8_10 | Fixed | RHSA-2026:2220 |
| Red Hat Enterprise Linux 8.2 Advanced Update Support | firefox-0:140.7.0-1.el8_2 | Fixed | RHSA-2026:2074 |
| Red Hat Enterprise Linux 8.2 Advanced Update Support | thunderbird-0:140.7.0-1.el8_2 | Fixed | RHSA-2026:1471 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | firefox-0:140.7.0-1.el8_4 | Fixed | RHSA-2026:2073 |
| Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | thunderbird-0:140.7.0-1.el8_4 | Fixed | RHSA-2026:1461 |
| Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | firefox-0:140.7.0-1.el8_4 | Fixed | RHSA-2026:2073 |
| Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | thunderbird-0:140.7.0-1.el8_4 | Fixed | RHSA-2026:1461 |
| Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | firefox-0:140.7.0-1.el8_6 | Fixed | RHSA-2026:2070 |
| Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | thunderbird-0:140.7.0-1.el8_6 | Fixed | RHSA-2026:1487 |
| Red Hat Enterprise Linux 8.6 Telecommunications Update Service | firefox-0:140.7.0-1.el8_6 | Fixed | RHSA-2026:2070 |
| Red Hat Enterprise Linux 8.6 Telecommunications Update Service | thunderbird-0:140.7.0-1.el8_6 | Fixed | RHSA-2026:1487 |
| Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions | firefox-0:140.7.0-1.el8_6 | Fixed | RHSA-2026:2070 |
| Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions | thunderbird-0:140.7.0-1.el8_6 | Fixed | RHSA-2026:1487 |
| Red Hat Enterprise Linux 8.8 Telecommunications Update Service | firefox-0:140.7.0-1.el8_8 | Fixed | RHSA-2026:2069 |
| Red Hat Enterprise Linux 8.8 Telecommunications Update Service | thunderbird-0:140.7.0-1.el8_8 | Fixed | RHSA-2026:1462 |
| Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions | firefox-0:140.7.0-1.el8_8 | Fixed | RHSA-2026:2069 |
| Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions | thunderbird-0:140.7.0-1.el8_8 | Fixed | RHSA-2026:1462 |
| Red Hat Enterprise Linux 9 | firefox-0:140.7.0-1.el9_7 | Fixed | RHSA-2026:0694 |
| Red Hat Enterprise Linux 9 | thunderbird-0:140.7.0-1.el9_7 | Fixed | RHSA-2026:0924 |
| Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions | firefox-0:140.7.0-1.el9_0 | Fixed | RHSA-2026:2047 |
| Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions | thunderbird-0:140.7.0-1.el9_0 | Fixed | RHSA-2026:1413 |
| Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions | firefox-0:140.7.0-1.el9_2 | Fixed | RHSA-2026:2044 |
| Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions | thunderbird-0:140.7.0-1.el9_2 | Fixed | RHSA-2026:1415 |
| Red Hat Enterprise Linux 9.4 Extended Update Support | firefox-0:140.7.0-1.el9_4 | Fixed | RHSA-2026:2041 |
| Red Hat Enterprise Linux 9.4 Extended Update Support | thunderbird-0:140.7.0-1.el9_4 | Fixed | RHSA-2026:1414 |
| Red Hat Enterprise Linux 9.6 Extended Update Support | firefox-0:140.7.0-1.el9_6 | Fixed | RHSA-2026:2043 |
| Red Hat Enterprise Linux 9.6 Extended Update Support | thunderbird-0:140.7.0-2.el9_6 | Fixed | RHSA-2026:1320 |
| Red Hat Enterprise Linux 10 | rhel10/firefox-flatpak | Affected | n/a |
| Red Hat Enterprise Linux 10 | rhel10/thunderbird-flatpak | Affected | n/a |
| Red Hat Enterprise Linux 6 | firefox | Out of support scope | n/a |
| Red Hat Enterprise Linux 6 | thunderbird | Out of support scope | n/a |
| Red Hat Enterprise Linux 7 | thunderbird | Out of support scope | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.
Metrics
No CVSS v4.0 score for this CVE.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
1 other source (Red Hat) ▾
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
No CVSS v3.0 score for this CVE.
No CVSS v2.0 score for this CVE.
This CVE is not in the KEV list.
CISA SSVC (Vulnrichment)
Stakeholder-Specific Vulnerability Categorization from CISA ADP.
Exploitation
NoneAutomatable
NoTechnical Impact
TotalDecision
n/aAssessed Jan 15, 2026 · SSVC 2.0.3
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 3, 2026.
Score over time
Jan–Oct 2026- EPSS v4
- EPSS v5
Percentile over time
- EPSS v4
- EPSS v5
Table of values (3 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 3, 2026 | 0.48% (0.00482) | 39.41th | v5 (v2026.06.15) |
| Jun 15, 2026 | 0.39% (0.00389) | 30.50th | v5 (v2026.06.15) |
| Jan 14, 2026 | 0.04% (0.00040) | 12.19th | v4 (v2025.03.14) |
References (35)
- https://access.redhat.com/errata/RHSA-2026:0667
- https://access.redhat.com/errata/RHSA-2026:0694
- https://access.redhat.com/errata/RHSA-2026:0924
- https://access.redhat.com/errata/RHSA-2026:1320
- https://access.redhat.com/errata/RHSA-2026:1413
- https://access.redhat.com/errata/RHSA-2026:1414
- https://access.redhat.com/errata/RHSA-2026:1415
- https://access.redhat.com/errata/RHSA-2026:1461
- https://access.redhat.com/errata/RHSA-2026:1462
- https://access.redhat.com/errata/RHSA-2026:1471
- https://access.redhat.com/errata/RHSA-2026:1487
- https://access.redhat.com/errata/RHSA-2026:2041
- https://access.redhat.com/errata/RHSA-2026:2043
- https://access.redhat.com/errata/RHSA-2026:2044
- https://access.redhat.com/errata/RHSA-2026:2047
- https://access.redhat.com/errata/RHSA-2026:2069
- https://access.redhat.com/errata/RHSA-2026:2070
- https://access.redhat.com/errata/RHSA-2026:2073
- https://access.redhat.com/errata/RHSA-2026:2074
- https://access.redhat.com/errata/RHSA-2026:2220
- https://access.redhat.com/errata/RHSA-2026:2231
- https://access.redhat.com/errata/RHSA-2026:2271
- https://access.redhat.com/errata/RHSA-2026:2286
- https://access.redhat.com/security/cve/CVE-2026-0891 Vendor Advisory
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=1964722%2C2000981%2C2003100%2C2003278 Broken Link
- https://bugzilla.redhat.com/show_bug.cgi?id=2428963 Issue Tracking
- https://nvd.nist.gov/vuln/detail/CVE-2026-0891
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-0891.json
- https://www.cve.org/CVERecord?id=CVE-2026-0891
- https://www.mozilla.org/security/advisories/mfsa2026-01/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-03/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-03/#CVE-2026-0891
- https://www.mozilla.org/security/advisories/mfsa2026-04/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-05/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-05/#CVE-2026-0891
Change history (0)
No recorded changes yet.