CVE-2025-39878

5.5 MEDIUM 0.2% exploit odds Fix listed Memory safety OS & kernel

What it is

In the Linux kernel, the following vulnerability has been resolved: ceph: fix crash after fscrypt_encrypt_pagecache_blocks() error The function move_dirty_folio_in_page_array() was created by commit ce80b76dd327 ("ceph: introduce ceph_process_folio_batch() method") by moving code from ceph_writepages_start() to this function. This new function is supposed to return an error code which is checked by the caller (now ceph_process_folio_batch()), and on error, the caller invokes redirty_page_for_writepage() and then breaks from the loop. However, the refactoring commit has gone wrong, and it by accident, it always returns 0 (= success) because it first NULLs the pointer and then returns PTR_ERR(NULL) which is always 0. This means errors are silently ignored, leaving NULL entries in the page array, which may later crash the kernel. The simple solution is to call PTR_ERR() before clearing the pointer.

At a glance

Exploitability: Can be exploited locally on the machine with a low-privilege account. High risk of service disruption.
Exploit odds: 0.2% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2025-09-23 06:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-21 13:18 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.2% in the next 30 days (EPSS).
Severity: 5.5 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2025-09-23 06:15 UTC
Last modified: 2026-10-21 13:18 UTC
Exploit probability: 0.2% · EPSS, next 30 days
Weakness: CWE-476 · NULL pointer dereference
Record status: Modified

Affected

Linux Kernel < 6.16.8
Linux Kernel 6.17

Attack profile CVSS 3.1 · 5.5

Attack vector: Local
Complexity: Low
Privileges needed: Low
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Raw vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Is it in your code?

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Read https://cve-list.com/agent/cve/CVE-2025-39878.md and follow it. Check whether this project is affected by CVE-2025-39878. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record