SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2023-5941

Depending on the nature of an application that calls libc's stdio functions and the presence of errors returned from the write(2) system call (or an overridden stdio write routine) a heap buffer overflow may occur.

CRITICAL 9.8EPSS 1.07%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (1.07%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

In versions of FreeBSD 12.4-RELEASE prior to 12.4-RELEASE-p7 and FreeBSD 13.2-RELEASE prior to 13.2-RELEASE-p5 the __sflush() stdio function in libc does not correctly update FILE objects' write space members for write-buffered streams when the write(2) system call returns an error.  Depending on the nature of an application that calls libc's stdio functions and the presence of errors returned from the write(2) system call (or an overridden stdio write routine) a heap buffer overflow may occur. Such overflows may lead to data corruption or the execution of arbitrary code at the privilege level of the calling program.

CVSS 3.1
9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
1.07% probability · 65th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-131, CWE-787
Affected
freebsd/freebsd
Source
secteam@freebsd.org
EPSS trend
0%3%5%26 October 2026: 1.07%26 October 202626 October 2026

EPSS 1.1% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.