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

> 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.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-101387, BELL-CVE-2026-89962, DEBIAN-CVE-2026-89962, GHSA-52p7-4c9h-jcc7, UBUNTU-CVE-2026-89962

## 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.

## Is CVE-2026-89962 being exploited?

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

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89962 and fix it if it is affected.

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

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-89962/ (Markdown: https://insights.sbomify.com/CVE-2026-89962/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89962
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89962
- OSV: https://osv.dev/vulnerability/CVE-2026-89962

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-89962/
Summaries are generated and may contain mistakes; the official description above is the record.