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01 Record

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,

UnratedPUBLISHEDCNA: mozilla
CNA base scoreUnratedNo CNA CVSS vector
View raw JSON

02 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,

03 Exploitation and scoring

Exploitation
Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.
SSVC decision
Not assessed by CISA
EPSS probability
0.66% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 51.6% of scored records. A rank, not a probability.
NVD base score
5.3 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
NVD analysis status
Modified. NVD last modified this record on 2026-06-17.
Red Hat severity
Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2023-12-19 13:38Z2 YR AGO
Last updated
2025-02-13 17:26Z1 YR AGO
Reserved
2023-12-15
Assigning CNA
mozilla
Record state
PUBLISHED
Severity
Not rated by the issuing CNA
CNA CVSS vector
Not published by the issuing CNA
Weaknesses
  • CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')Class
  • CWE-363Race Condition Enabling Link FollowingBase
Data version
5.1
Document digest
78b0394e6db1fc75d4d51ebd44ef3b90117ce11c3f63229a827f707bb4d87daa

05 Affected products

VendorProductVersionsPlatforms
MozillaFirefox ESR< 115.6—
MozillaThunderbird< 115.6—
MozillaFirefox< 121—

06 References

07 Fixed in

AlmaLinux 8

  • firefox
    Fixed in 115.6.0-1.el8_9.alma
  • thunderbird
    Fixed in 115.6.0-1.el8_9.alma

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

AlmaLinux 9

  • firefox
    Fixed in 115.6.0-1.el9_3.alma
  • firefox-x11
    Fixed in 115.6.0-1.el9_3.alma
  • thunderbird
    Fixed in 115.6.0-1.el9_3.alma

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 8

  • firefox
    Fixed in 115.6.0-1.el8_9.alma
  • thunderbird
    Fixed in 115.6.0-1.el8_9.alma

Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 9

  • firefox
    Fixed in 115.6.0-1.el9_3.alma
  • firefox-x11
    Fixed in 115.6.0-1.el9_3.alma
  • thunderbird
    Fixed in 115.6.0-1.el9_3.alma

Derived from AlmaLinux 9. Partial coverage: only packages taken from AlmaLinux 9 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

Debian 12

  • firefox-esr
    Fixed in 115.6.0esr-1~deb12u1
  • thunderbird
    Fixed in 1:115.6.0-1~deb12u1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • firefox-esr
    Fixed in 115.6.0esr-1
  • thunderbird
    Fixed in 1:115.6.0-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • firefox-esr
    Fixed in 115.6.0esr-1
  • thunderbird
    Fixed in 1:115.6.0-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 18.04 LTS

  • mozjs38
    No fix yet
  • mozjs52
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 20.04 LTS

  • firefox
    Fixed in 121.0+build1-0ubuntu0.20.04.1
  • mozjs52
    No fix yet
  • mozjs68
    No fix yet
  • thunderbird
    Fixed in 1:115.6.0+build2-0ubuntu0.20.04.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 22.04 LTS

  • mozjs102
    No fix yet
  • mozjs78
    No fix yet
  • mozjs91
    No fix yet
  • thunderbird
    Fixed in 1:115.6.0+build2-0ubuntu0.22.04.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 24.04 LTS

  • mozjs102
    No fix yet
  • thunderbird
    Fixed in 1:115.6.0+build2-0ubuntu1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.