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CVE-2023-6857

MEDIUM
5.3
CVSS Score
Published: December 19, 2023 at 01:38 PM UTC
Updated: June 17, 2026 at 06:51 AM UTC
4 products affected across 2 vendorsDebian LinuxFirefoxThunderbird· also runs on 3 platforms

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.7%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Debian Linux· Debiandrupal
95%
10.011.012.0
Firefox· Mozilla
95%
v < 121
Affected range stops below 121, so it looks safe — our inference, not a vendor statement
Affected range stops below 121.0, so it looks safe — our inference, not a vendor statement
apple-macos (environment) · google-android (environment) · linux-linux-kernel (environment)
Firefox ESR· Mozilla
95%
v < 115.6
Affected range stops below 115.6, so it looks safe — our inference, not a vendor statement
apple-macos (environment) · google-android (environment) · linux-linux-kernel (environment)
Thunderbird· Mozilla
95%
v < 115.6
Affected range stops below 115.6, so it looks safe — our inference, not a vendor statement
apple-macos (environment) · google-android (environment) · linux-linux-kernel (environment)

Runs on — not affected

The affected product only carries this flaw when running on these platforms. The platforms themselves are not vulnerable.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (9)

Issue TrackingPermissions Required
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1796023
Mailing ListThird Party Advisory
Source: [email protected]
https://lists.debian.org/debian-lts-announce/2023/12/msg00020.html
Mailing ListThird Party Advisory
Source: [email protected]
https://lists.debian.org/debian-lts-announce/2023/12/msg00021.html
Third Party Advisory
Source: [email protected]
https://security.gentoo.org/glsa/202401-10
Third Party Advisory
Source: [email protected]
https://www.debian.org/security/2023/dsa-5581
Third Party Advisory
Source: [email protected]
https://www.debian.org/security/2023/dsa-5582
Vendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2023-54/
Vendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2023-55/

CVSS

5.3MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-362

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