FreeBSD Kernel OOB Heap Write via rfork Core Dump Mutation
CVE-2026-58088 Published on August 19, 2026
Race condition in ELF core dump segment counting
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.
An unprivileged local user sharing an address space with a process that dumps core can trigger an out-of-bounds write on the kernel heap, potentially leading to privilege escalation.
Vulnerability Analysis
CVE-2026-58088 is exploitable with local system access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Types
What is a Race Condition Vulnerability?
The program contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.
CVE-2026-58088 has been classified to as a Race Condition vulnerability or weakness.
What is a Memory Corruption Vulnerability?
The software writes data past the end, or before the beginning, of the intended buffer. Typically, this can result in corruption of data, a crash, or code execution. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent write operation then produces undefined or unexpected results.
CVE-2026-58088 has been classified to as a Memory Corruption vulnerability or weakness.
Products Associated with CVE-2026-58088
Want to know whenever a new CVE is published for FreeBSD? stack.watch will email you.
Affected Versions
FreeBSD:- Version 15.1-RELEASE and below p2 is affected.
- Version 15.0-RELEASE and below p12 is affected.
- Version 14.4-RELEASE and below p8 is affected.