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

CVE-2026-89962 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-89962, released September 23, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-89962
- Priority: High
- CVSS: 7.1 (Moderate)
- EPSS: 0.0023
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 16, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-89962

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.111-1 | [DEBIAN-CVE-2026-89962](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89962.md) | Sep 23, 2026 |
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-89962](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89962.md) | Sep 23, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.111-1~deb12u1 | [DEBIAN-CVE-2026-89962](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89962.md) | Sep 23, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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