CVE-2026-39461 json
select(2) file descriptor set overflow causes stack overflow
published 2026-05-21 5 mo ago modified 2026-07-23 3 mo ago also EUVD-2026-31258
- cvss
- 8.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 6%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- FreeBSD FreeBSD p5, p9, p14
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 5 mo ago
Exploit prediction
0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 8.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
| CNA | 3.1 | 8.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H |
Affected products
- FreeBSD FreeBSD
Classification
- Weakness
-
- CWE-121 Stack-based Buffer Overflow
References
-
security.freebsd.org
/advisories/FreeBSD-SA-26:22.libcasper.asc
vendor-advisory
Sources
- CVE List CVE-2026-39461
- NVD CVE-2026-39461
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