CVE-2026-58088 FreeBSD CVE debrief

Who should care

System administrators and security teams responsible for FreeBSD systems, particularly those running versions 14.4, 15.0, and 15.1, should assess exposure and prioritize remediation. They should verify inventory of FreeBSD systems, check for core dump configurations, and monitor system logs for potential exploitation attempts. Additionally, they should review compensating controls for exposed systems while remediation is scheduled and verified, and track

Why it matters

CVE-2026-58088 is a high-severity vulnerability in the FreeBSD ELF core dump code that can lead to privilege escalation. System administrators and security teams should assess exposure and prioritize remediation for systems running affected versions.

• Potential privilege escalation via out-of-bounds write on kernel heap
• Increased risk of system compromise for unprivileged local users
• Possible denial-of-service or system instability
• Need for verification of affected versions and exposure

Technical summary

The ELF core dump code counted the number of dumpable VM map entries, allocated a buffer for the corresponding program headers, then iterated over the map a second time to populate them. A process sharing the address space via rfork(2) can mutate the map between the two passes, causing the second pass to write program headers past the end of the buffer. This vulnerability can be triggered by an unprivileged local user sharing an address space with a process that dumps core, potentially leading to privilege escalation. The vulnerability affects FreeBSD systems, particularly those running versions 14.4, 15.0, and 15.1.

Defensive priority

High-priority assessment and remediation recommended for systems running FreeBSD 14.4, 15.0, and 15.1.

Recommended defensive actions

• Assess exposure and prioritize remediation for systems running FreeBSD 14.4, 15.0, and 15.1
• Verify inventory of FreeBSD systems and check for core dump configurations
• Monitor system logs for potential exploitation attempts
• Apply vendor patches or updates as available
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The ELF core dump code has a vulnerability where a process sharing the address space via rfork(2) can mutate the map between two passes, causing the second pass to write program headers past the end of the buffer.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.