Use after free in Mozilla Firefox ESR
Priority MEDIUM 42CWE-416Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Partial Red Hat: 18 fixed, 1 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-416 and the CVSS impact.
Summary
A use-after-free was identified in the `nsDNSService::Init`. This issue appears to manifest rarely during start-up. This vulnerability affects Firefox ESR < 115.6 and Thunderbird < 115.6.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00951 61st percentileScored 2026-11-07
Fix Partial Firefox ESR (Mozilla): 115.6Thunderbird (Mozilla): 115.6Red Hat: 18 advisoriesRed Hat: 18 fixed, 1 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Mozilla | Firefox ESR | before 115.6 | 115.6 | Patch available | CNA |
| Mozilla | Thunderbird | before 115.6 | 115.6 | Patch available | CNA |
- Firefox ESR VendorMozilla Affected before 115.6 Fixed in 115.6 Patch available CNA
- Thunderbird VendorMozilla Affected before 115.6 Fixed in 115.6 Patch available CNA
CPE configurations NVD · 5
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* | before 115.6 | Vulnerable | Mozilla |
| cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* | before 115.6 | Vulnerable | Mozilla |
| cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* | 10.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* | 11.0 | Vulnerable | Debian |
| cpe:2.3:o:debian:debian_linux:12.0:*:*:*:*:*:*:* | 12.0 | Vulnerable | Debian |
- cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* Versions before 115.6 Vulnerable ·Mozilla
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 115.6 Vulnerable ·Mozilla
- cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* Versions 10.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* Versions 11.0 Vulnerable ·Debian
- cpe:2.3:o:debian:debian_linux:12.0:*:*:*:*:*:*:* Versions 12.0 Vulnerable ·Debian
Remediation
- Fix · CNA Firefox ESR (Mozilla) Fixed in 115.6
- Fix · CNA Thunderbird (Mozilla) Fixed in 115.6
Red Hat 18 advisories
- RHSA-2024:0027 Released 2024-01-02 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux Client (v. 7) thunderbird-115.6.0-1.el7_9
- Red Hat Enterprise Linux Server Optional (v. 7) thunderbird-115.6.0-1.el7_9
- Red Hat Enterprise Linux Workstation (v. 7) thunderbird-115.6.0-1.el7_9
- RHSA-2024:0029 Released 2024-01-02 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream EUS (v.9.2) thunderbird-115.6.0-1.el9_2
- RHSA-2024:0023 Released 2024-01-02 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream AUS (v. 8.2) firefox-115.6.0-1.el8_2
- Red Hat Enterprise Linux AppStream E4S (v. 8.2) firefox-115.6.0-1.el8_2
- Red Hat Enterprise Linux AppStream TUS (v. 8.2) firefox-115.6.0-1.el8_2
Show 15 more Red Hat advisories
- RHSA-2024:0030 Released 2024-01-02 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream AUS (v. 8.2) thunderbird-115.6.0-1.el8_2
- Red Hat Enterprise Linux AppStream E4S (v. 8.2) thunderbird-115.6.0-1.el8_2
- Red Hat Enterprise Linux AppStream TUS (v. 8.2) thunderbird-115.6.0-1.el8_2
- RHSA-2024:0028 Released 2024-01-02 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream AUS (v.8.4) thunderbird-115.6.0-1.el8_4
- Red Hat Enterprise Linux AppStream E4S (v.8.4) thunderbird-115.6.0-1.el8_4
- Red Hat Enterprise Linux AppStream TUS (v.8.4) thunderbird-115.6.0-1.el8_4
- RHSA-2024:0026 Released 2024-01-02 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux Client (v. 7) firefox-115.6.0-1.el7_9
- Red Hat Enterprise Linux Client Optional (v. 7) firefox-115.6.0-1.el7_9
- Red Hat Enterprise Linux Server (v. 7) firefox-115.6.0-1.el7_9
- Red Hat Enterprise Linux Server Optional (v. 7) firefox-115.6.0-1.el7_9
- Red Hat Enterprise Linux Workstation (v. 7) firefox-115.6.0-1.el7_9
- Red Hat Enterprise Linux Workstation Optional (v. 7) firefox-115.6.0-1.el7_9
- RHSA-2024:0003 Released 2024-01-02 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream (v. 8) thunderbird-115.6.0-1.el8_9
- RHSA-2024:0024 Released 2024-01-02 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream EUS (v.8.6) firefox-115.6.0-1.el8_6
- RHSA-2024:0022 Released 2024-01-02 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream EUS (v.9.0) firefox-115.6.0-1.el9_0
- RHSA-2024:0021 Released 2024-01-02 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox-115.6.0-1.el8_4
- Red Hat Enterprise Linux AppStream E4S (v.8.4) firefox-115.6.0-1.el8_4
- Red Hat Enterprise Linux AppStream TUS (v.8.4) firefox-115.6.0-1.el8_4
- RHSA-2024:0025 Released 2024-01-02 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream (v. 9) firefox-115.6.0-1.el9_3, firefox-x11-115.6.0-1.el9_3
- RHSA-2024:0019 Released 2024-01-02 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream EUS (v.9.2) firefox-115.6.0-1.el9_2, firefox-x11-115.6.0-1.el9_2
- RHSA-2024:0011 Released 2024-01-02 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream EUS (v.8.8) firefox-115.6.0-1.el8_8
- RHSA-2024:0012 Released 2024-01-02 · Red Hat rating Importantfirefox security update
- Red Hat Enterprise Linux AppStream (v. 8) firefox-115.6.0-1.el8_9
- RHSA-2024:0005 Released 2024-01-02 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream EUS (v.8.6) thunderbird-115.6.0-1.el8_6
- RHSA-2024:0004 Released 2024-01-02 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream EUS (v.8.8) thunderbird-115.6.0-1.el8_8
- RHSA-2024:0002 Released 2024-01-02 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream EUS (v.9.0) thunderbird-115.6.0-1.el9_0
- RHSA-2024:0001 Released 2024-01-02 · Red Hat rating Importantthunderbird security update
- Red Hat Enterprise Linux AppStream (v. 9) thunderbird-115.6.0-1.el9_3
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
Mozilla Firefox ESR 115.6
11 records Highest priority Priority MEDIUM 7 MEDIUM, 4 LOW
Other records, highest priority first
- TI-2023-06261 Out-of-bounds write in Mozilla Firefox ESRPriority MEDIUM 57
- TI-2023-06263 Out-of-bounds write in Mozilla Firefox ESRPriority MEDIUM 43
- TI-2023-06266 Out-of-bounds write in Mozilla Firefox ESRPriority MEDIUM 41
- Release ·
Mozilla Thunderbird 115.6
11 records Highest priority Priority MEDIUM 7 MEDIUM, 4 LOW
Other records, highest priority first
- TI-2023-06261 Out-of-bounds write in Mozilla Firefox ESRPriority MEDIUM 57
- TI-2023-06263 Out-of-bounds write in Mozilla Firefox ESRPriority MEDIUM 43
- TI-2023-06266 Out-of-bounds write in Mozilla Firefox ESRPriority MEDIUM 41
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2024:0003, RHSA-2024:0012 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2024:0001, RHSA-2024:0025 |
| Red Hat Enterprise Linux AppStream AUS (v. 8.2) | Fixed | RHSA-2024:0023, RHSA-2024:0030 |
| Red Hat Enterprise Linux AppStream AUS (v.8.4) | Fixed | RHSA-2024:0021, RHSA-2024:0028 |
| Red Hat Enterprise Linux AppStream E4S (v. 8.2) | Fixed | RHSA-2024:0023, RHSA-2024:0030 |
| Red Hat Enterprise Linux AppStream E4S (v.8.4) | Fixed | RHSA-2024:0021, RHSA-2024:0028 |
| Red Hat Enterprise Linux AppStream EUS (v.8.6) | Fixed | RHSA-2024:0005, RHSA-2024:0024 |
| Red Hat Enterprise Linux AppStream EUS (v.8.8) | Fixed | RHSA-2024:0004, RHSA-2024:0011 |
| Red Hat Enterprise Linux AppStream EUS (v.9.0) | Fixed | RHSA-2024:0002, RHSA-2024:0022 |
| Red Hat Enterprise Linux AppStream EUS (v.9.2) | Fixed | RHSA-2024:0019, RHSA-2024:0029 |
| Red Hat Enterprise Linux AppStream TUS (v. 8.2) | Fixed | RHSA-2024:0023, RHSA-2024:0030 |
| Red Hat Enterprise Linux AppStream TUS (v.8.4) | Fixed | RHSA-2024:0021, RHSA-2024:0028 |
| Red Hat Enterprise Linux Client (v. 7) | Fixed | RHSA-2024:0026, RHSA-2024:0027 |
| Red Hat Enterprise Linux Client Optional (v. 7) | Fixed | RHSA-2024:0026 |
| Red Hat Enterprise Linux Server (v. 7) | Fixed | RHSA-2024:0026 |
| Red Hat Enterprise Linux Server Optional (v. 7) | Fixed | RHSA-2024:0026, RHSA-2024:0027 |
| Red Hat Enterprise Linux Workstation (v. 7) | Fixed | RHSA-2024:0026, RHSA-2024:0027 |
| Red Hat Enterprise Linux Workstation Optional (v. 7) | Fixed | RHSA-2024:0026 |
Timeline
- 2026-10-02 Threatist record created from CVE-2023-6862
- 2026-10-03 Alias added: GHSA-5x56-7cpg-238g
References
Advisory 7
- https://www.mozilla.org/security/advisories/mfsa2023-54/
- https://www.mozilla.org/security/advisories/mfsa2023-55/
- https://www.debian.org/security/2023/dsa-5581
- https://www.debian.org/security/2023/dsa-5582
- https://lists.debian.org/debian-lts-announce/2023/12/msg00020.html
- https://lists.debian.org/debian-lts-announce/2023/12/msg00021.html
- https://security.gentoo.org/glsa/202401-10
More Mozilla Firefox Esr vulnerabilities
- TI-2022-15364 Use after free in Mozilla Firefox CVSS 3.1CRITICAL 9.8
- TI-2022-13633 Out-of-bounds write in Mozilla Thunderbird CVSS 3.1CRITICAL 9.8
- TI-2021-03015 XML injection in Mozilla Firefox ESR CVSS 3.1CRITICAL 10.0
- TI-2022-09755 Protection mechanism failure in Mozilla Firefox CVSS 3.1CRITICAL 9.6
- TI-2022-07009 Protection mechanism failure in Mozilla Firefox CVSS 3.1CRITICAL 9.6
- TI-2023-18834 Use after free in Mozilla Firefox CVSS 3.1HIGH 8.8
Sources
- CVE-2023-6862 · CVE Program
- CVE-2023-6862 · NVD
- FIRST EPSS
- GHSA-5x56-7cpg-238g · GitHub Advisory Database · CC BY 4.0
- CVE-2023-6862 · Red Hat security data · CC BY 4.0
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