CVE-2026-89962 powerpc/kexec_file: Prevent kexec range truncation

Q: Is CVE-2026-89962 being exploited?

There is no known exploitation of CVE-2026-89962 in the wild and no public exploit code.

Not scored Published 16 Sep 2026 Updated 21 Oct 2026

A logic error in Linux kernel kexec memory range merging can cause valid memory fragments to be lost, potentially allowing a crash kernel to overwrite active memory.

Exploited in the wild: Not known
Login needed: An administrator
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-89962?

CVE-2026-89962 is a memory corruption vulnerability in Linux, published on 16 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

powerpc/kexec_file: Prevent kexec range truncation

Sashiko AI review pointed out the following issue.

The __merge_memory_ranges() function incorrectly handles overlapping memory ranges when merging them. Although sort_memory_ranges() sorts all ranges by their start address in ascending order beforehand, the merge logic remains defective in two ways:

1. It compares the current range's start against the previous element (i-1) instead of the running target index (idx)

2. It unconditionally overwrites 'ranges[idx].end' with 'ranges[i].end'.

This logic flaw leads to critical memory truncation when a larger memory range completely subsumes subsequent smaller ranges.

For example, consider a sorted input array with three ranges: Range A (idx=0): [0x1000 - 0x9000] Range B (i=1): [0x2000 - 0x5000] (completely inside Range A) Range C (i=2): [0x6000 - 0x8000] (completely inside Range A)

1. When i=1 (Range B): ranges[1].start (0x2000) <= ranges[0].end + 1 (0x9001) is TRUE. The code executes: ranges[0].end = ranges[1].end, which erroneously shrinks Range A's end from 0x9000 down to 0x5000.

2. When i=2 (Range C): ranges[2].start (0x6000) <= ranges[1].end + 1 (0x5001) is FALSE. The code falls into the else block, creating a broken new range.

As a result, valid memory fragments [0x5001 - 0x5fff] and [0x8001 - 0x9000] are completely lost from the kexec exclude lists, potentially allowing the crash kernel to overwrite active memory, causing data corruption or crashes.

Fix this by ensuring the start of the current range is compared against the end of the active merged range (idx), and use max() to safely prevent the outer boundary from being truncated.

Which versions are affected by CVE-2026-89962?

How do I fix CVE-2026-89962?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-89962 being exploited?