CVE-2025-39878: In the Linux kernel, the following vulnerability has been resolved: ceph: fix crash after fscrypt_encrypt_pagecache_blocks() error The function move_dirty

In the Linux kernel, the following vulnerability has been resolved: ceph: fix crash after fscrypt_encrypt_pagecache_blocks() error The function move_dirty_fol

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.

Description from the National Vulnerability Database, published by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

What it means for a small business

Linux is on the computers, phones or browsers your team uses every day. Turn on automatic updates and restart: most of these fixes only take effect after a restart.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.19%, higher than 8% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 2026, updated daily.

Check your own setup

Website check: reads what your site runs from the outside (WordPress version, plugins it can see, old server software) and matches it against this database.
Server check: what your web server says about itself, and whether that version has known flaws.

Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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