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CVE-2026-57589 OpenBSD CVE debrief

A use-after-free vulnerability was discovered in OpenBSD 7.9, specifically in the sys/kern/sysv_sem.c file. This vulnerability, tracked as CVE-2026-57589, occurs in the sys_semget() function after a context switch using tsleep. Successful exploitation of this bug can lead to local privilege escalation to root. The vulnerability allows an attacker to access memory after it has been freed, which can cause the system to crash or allow the attacker to execute arbitrary code. System administrators and security teams should be aware of this vulnerability and take immediate action to mitigate the risk. Evidence is limited to public sources and may not reflect the full scope or impact of the vulnerability.

Vendor
OpenBSD
Product
Unknown
CVSS
HIGH 7.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-25
Original CVE updated
2026-07-10
Advisory published
2026-06-25
Advisory updated
2026-07-10

Who should care

System administrators and security teams responsible for OpenBSD systems, particularly those using version 7.9, should be aware of this vulnerability and take immediate action to mitigate the risk.

Technical summary

The vulnerability is caused by a use-after-free error in the sys_semget() function, which is part of the sys/kern/sysv_sem.c file in OpenBSD 7.9. This error occurs when the function is called after a context switch using tsleep, allowing an attacker to escalate privileges to root. The vulnerability is a result of the system's failure to properly handle memory allocation and deallocation. An attacker can exploit this vulnerability by triggering the use-after-free condition, which can lead to a system crash or arbitrary code execution. The CVE record was published on 2026-06-25T01:16:26.537Z and was last modified on 2026-07-10T16:39:52.480Z. The NVD entry is currently Analyzed.

Defensive priority

High

Recommended defensive actions

  • Apply the official patch provided by OpenBSD to update the sys/kern/sysv_sem.c file.
  • Implement compensating controls, such as restricting access to sensitive areas of the system.
  • Monitor system logs for suspicious activity related to the sys_semget() function.
  • Perform regular inventory checks to ensure all OpenBSD systems are up-to-date with the latest security patches.
  • Review system configurations to ensure that access controls are properly implemented.
  • Conduct regular security audits to identify potential vulnerabilities.
  • Implement additional security measures, such as intrusion detection and prevention systems.

Evidence notes

The CVE record was published on 2026-06-25T01:16:26.537Z and was last modified on 2026-07-10T16:39:52.480Z. The NVD entry is currently Analyzed. The vulnerability has a CVSS score of 7.4 and is classified as HIGH severity. Evidence is limited to public sources and may not reflect the full scope or impact of the vulnerability. Defenders should verify affected systems and apply patches or mitigations as recommended by the vendor.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-06-25T01:16:26.537Z and has not been modified since then. The NVD entry is currently Analyzed.