CVE-2023-5941 | libc stdio buffer overflow

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.

Published: 2023-11-08 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-5941 is rated Moderate Risk (60.6/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 1.07%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-5941

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.85% 1.07% +0.22%
2 2026-06-06 0.87% 0.85% -0.02%
3 2025-12-28 — 0.87% —

Full EPSS history (19 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-5941

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2023-5941

Affected software / configurations for CVE-2023-5941

Vendor Product Version Raw CPE
freebsd freebsd < 12.4 cpe:2.3:o:freebsd:freebsd:*:*:*:*:*:*:*:*
freebsd freebsd >= 13.0, < 13.2 cpe:2.3:o:freebsd:freebsd:*:*:*:*:*:*:*:*
freebsd freebsd 12.4 cpe:2.3:o:freebsd:freebsd:12.4:-:*:*:*:*:*:*
freebsd freebsd 12.4 cpe:2.3:o:freebsd:freebsd:12.4:p1:*:*:*:*:*:*
freebsd freebsd 12.4 cpe:2.3:o:freebsd:freebsd:12.4:p2:*:*:*:*:*:*
freebsd freebsd 12.4 cpe:2.3:o:freebsd:freebsd:12.4:p3:*:*:*:*:*:*
freebsd freebsd 12.4 cpe:2.3:o:freebsd:freebsd:12.4:p4:*:*:*:*:*:*
freebsd freebsd 12.4 cpe:2.3:o:freebsd:freebsd:12.4:p5:*:*:*:*:*:*
freebsd freebsd 12.4 cpe:2.3:o:freebsd:freebsd:12.4:p6:*:*:*:*:*:*
freebsd freebsd 12.4 cpe:2.3:o:freebsd:freebsd:12.4:rc2-p1:*:*:*:*:*:*
freebsd freebsd 12.4 cpe:2.3:o:freebsd:freebsd:12.4:rc2-p2:*:*:*:*:*:*
freebsd freebsd 13.2 cpe:2.3:o:freebsd:freebsd:13.2:-:*:*:*:*:*:*
freebsd freebsd 13.2 cpe:2.3:o:freebsd:freebsd:13.2:p1:*:*:*:*:*:*
freebsd freebsd 13.2 cpe:2.3:o:freebsd:freebsd:13.2:p2:*:*:*:*:*:*
freebsd freebsd 13.2 cpe:2.3:o:freebsd:freebsd:13.2:p3:*:*:*:*:*:*
freebsd freebsd 13.2 cpe:2.3:o:freebsd:freebsd:13.2:p4:*:*:*:*:*:*

References for CVE-2023-5941

cvelogic Threat Intelligence