# CVE-2026-89639: linux: In the Linux kernel, the following vulnerability has been resolved:  cifs: use cifs_invalidate_cache() in cifs_do_tru...

CVE-2026-89639 is fixed in linux on 1 platform by DEBIAN-CVE-2026-89639 (version 7.2.6-1), released September 23, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-89639
- Priority: High
- CVSS: 7.1 (high)
- EPSS: 0.0013
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 11, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:  cifs: use cifs_invalidate_cache() in cifs_do_truncate() for O_TRUNC  cifs_do_truncate() is invoked from cifs_open() without i_rwsem, so it cannot use cifs_resize_file_locked() to perform a proper fscache cookie resize.  Instead, add cifs_invalidate_cache() after cifs_setsize().  cifs_invalidate_cache() calls fscache_invalidate(), which works without holding i_rwsem: it unconditionally increments inval_counter and sets FSCACHE_COOKIE_NO_DATA_TO_READ, ensuring that stale cached data is not served once the cookie is later activated by fscache_use_cookie(). Truncation to zero leaves no valid cached data, making invalidation the correct semantic here.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-89639](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89639.md) | Sep 23, 2026 |

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Data as of 2026-11-08T06:59:42Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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