CVE-2026-58087: FreeBSD · Integer Underflow
Affects FreeBSDSource GCVE Database
Not known to be exploited · CVSS 7.8 High.
Data as of 27 Oct 2026, 14:14 UTC
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 19 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| FreeBSD FreeBSD | Affected
| Fixed in– |
AI-suggested
Until a patch is available, restrict unprivileged local user access where possible to mitigate exploitation risk.
Description
CVE-2026-58087 is an integer underflow vulnerability in FreeBSD's semctl(2) system call affecting the GETALL and SETALL commands. The flaw arises due to sequence number wrapping after 0x8000 create/destroy cycles of semaphore sets, allowing an attacker to bypass validation and cause out-of-bounds reads and writes on kernel heap memory. This can be exploited by an unprivileged local user to potentially escalate privileges. The vulnerability affects FreeBSD versions 14.4-RELEASE, 15.0-RELEASE, and 15.1-RELEASE. It has a high severity rating with a CVSS score of 7.8. No patch information is provided in the input data.