How severe is CVE-2023-6857?

CVE-2023-6857 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2023-6857 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-6857?

CVE-2023-6857 primarily affects Mozilla Firefox. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-6857?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2023-6857 published?

CVE-2023-6857 was published on 2023-12-19 and last updated on 2026-06-17.

CVE-2023-6857

CVE-2023-6857 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-362.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-362
Affected product: Mozilla Firefox
Published: 2023-12-19
Last modified: 2026-06-17

Description

When resolving a symlink, a race may occur where the buffer passed to `readlink` may actually be smaller than necessary. *This bug only affects Firefox on Unix-based operating systems (Android, Linux, MacOS). Windows is unaffected.* This vulnerability affects Firefox ESR < 115.6, Thunderbird < 115.6, and Firefox < 121.

Frequently asked questions

What is CVE-2023-6857?: When resolving a symlink, a race may occur where the buffer passed to `readlink` may actually be smaller than necessary. *This bug only affects Firefox on Unix-based operating systems (Android, Linux, MacOS). Windows is unaffected.* This vulnerability affects Firefox ESR < 115.6, Thunderbird < 115.6, and Firefox < 121.
How severe is CVE-2023-6857?: CVE-2023-6857 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2023-6857 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-6857?: CVE-2023-6857 primarily affects Mozilla Firefox. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-6857?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-6857 published?: CVE-2023-6857 was published on 2023-12-19 and last updated on 2026-06-17.

References

Affected products (6)

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:12.0:*:*:*:*:*:*:*

More vulnerabilities in Mozilla Firefox

CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
CVE-2026-4692 — Critical (CVSS 10.0): Sandbox escape in the Responsive Design Mode component. This vulnerability was fixed in Firefox 149, Firefox ESR…
CVE-2026-4689 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component. This vulnerability was…
CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
CVE-2026-2778 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability was fixed in…
CVE-2026-2776 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability…

All CVEs affecting Mozilla Firefox →

Other CWE-362 (Race Condition) vulnerabilities

CVE-2022-27626 — Critical (CVSS 10.0): A vulnerability regarding concurrent execution using shared resource with improper synchronization ('Race Condition')…
CVE-2015-8556 — Critical (CVSS 10.0): Local privilege escalation vulnerability in the Gentoo QEMU package before 2.5.0-r1.
CVE-2014-0703 — Critical (CVSS 10.0): Cisco Wireless LAN Controller (WLC) devices 7.4 before 7.4.110.0 distribute Aironet IOS software with a race condition…
CVE-2010-1228 — Critical (CVSS 10.0): Multiple race conditions in the sandbox infrastructure in Google Chrome before 4.1.249.1036 have unspecified impact and…
CVE-2008-6598 — Critical (CVSS 10.0): Multiple race conditions in WANPIPE before 3.3.6 have unknown impact and attack vectors related to "bri restart logic."
CVE-2026-46137 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: mptcp: pm: ADD_ADDR rtx: fix potential…

Browse all CWE-362 (Race Condition) vulnerabilities →