# CVE-2026-89840: f2fs: validate MOVE_RANGE destination size

CVE-2026-89840 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-89840, released September 23, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-89840
- Priority: High
- CVSS: 7.1 (Moderate)
- EPSS: 0.0017
- 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-2026-89840

## Description

In the Linux kernel, the following vulnerability has been resolved:  f2fs: validate MOVE_RANGE destination size  F2FS_IOC_MOVE_RANGE checks the source range, but not the destination end before updating i_size. A source hole can expose this: __clone_blkaddrs() skips NULL_ADDR entries and returns success, so the caller can still extend the destination inode with unchecked pos_out + len.  Reject destination overflow and use inode_newsize_ok() before extending the destination inode.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.113-1 | [DEBIAN-CVE-2026-89840](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89840.md) | Sep 23, 2026 |
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-89840](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89840.md) | Sep 23, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.113-1~deb12u1 | [DEBIAN-CVE-2026-89840](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89840.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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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