FreeBSD up to p4/p8/p13 libcasper stack-based overflow

CVSS Meta Temp Score
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CTI Interest Score
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8.1$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in FreeBSD up to p4/p8/p13. Impacted is the function libcasper. Executing a manipulation can lead to stack-based overflow. This vulnerability is handled as CVE-2026-39461. It is possible to launch the attack on the local host. There is not any exploit available. It is advisable to implement a patch to correct this issue.

Detailsinfo

A vulnerability classified as critical was found in FreeBSD up to p4/p8/p13. This vulnerability affects the function libcasper. The manipulation with an unknown input leads to a stack-based overflow vulnerability. The CWE definition for the vulnerability is CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

libcasper(3) communicates with helper processes via UNIX domain sockets, and uses the select(2) system call to wait for data to become available. However, it does not verify that its socket descriptor fits within select(2)'s descriptor set size limit of FD_SETSIZE (1024). An attacker able to cause an application using libcasper(3) to allocate large file descriptors, e.g., by opening many descriptors and executing a program which is not careful to close them upon startup, may trigger stack corruption. If the target application runs with setuid root privileges, this could be used to escalate local privileges.

The weakness was released with AISLE Research Team. The advisory is shared for download at security.freebsd.org. This vulnerability was named CVE-2026-39461 since 04/28/2026. The exploitation appears to be easy. The attack needs to be approached locally. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 05/24/2026).

Applying a patch is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1628). Once again VulDB remains the best source for vulnerability data.

Affected

  • FreeBSD Project FreeBSD OS

Productinfo

Type

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.3
VulDB Meta Temp Score: 8.1

VulDB Base Score: 7.8
VulDB Temp Score: 7.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

ADP CISA Base Score: 8.8
ADP CISA Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Stack-based overflow
CWE: CWE-121 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Timelineinfo

04/28/2026 CVE reserved
05/21/2026 +23 days Advisory disclosed
05/21/2026 +0 days VulDB entry created
05/24/2026 +3 days VulDB entry last update

Sourcesinfo

Product: freebsd.org

Advisory: security.freebsd.org
Organization: AISLE Research Team
Status: Confirmed

CVE: CVE-2026-39461 (🔒)
GCVE (CVE): GCVE-0-2026-39461
GCVE (VulDB): GCVE-100-364996
CERT Bund: WID-SEC-2026-1628 - FreeBSD Project FreeBSD OS: Mehrere Schwachstellen

Entryinfo

Created: 05/21/2026 12:49
Updated: 05/24/2026 05:39
Changes: 05/21/2026 12:49 (55), 05/21/2026 14:53 (7), 05/24/2026 05:39 (11)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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