CVE-2024-44947: fuse: Initialize beyond-EOF page contents before setting uptodate

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-09-02 · updated 2026-06-17
Weakness: CWE-665

Description

In the Linux kernel, the following vulnerability has been resolved: fuse: Initialize beyond-EOF page contents before setting uptodate fuse_notify_store(), unlike fuse_do_readpage(), does not enable page zeroing (because it can be used to change partial page contents). So fuse_notify_store() must be more careful to fully initialize page contents (including parts of the page that are beyond end-of-file) before marking the page uptodate. The current code can leave beyond-EOF page contents uninitialized, which makes these uninitialized page contents visible to userspace via mmap(). This is an information leak, but only affects systems which do not enable init-on-alloc (via CONFIG_INIT_ON_ALLOC_DEFAULT_ON=y or the corresponding kernel command line parameter).

Affected products

Linux kernel: from 2.6.36 before 4.19.321; from 4.20 before 5.4.283; from 5.5 before 5.10.225; from 5.11 before 5.15.166; from 5.16 before 6.1.107; from 6.2 before 6.6.48 — fixed in 4.19.321, 5.10.225, 5.15.166, 5.4.283, 6.1.107, 6.10.7

How to fix

Upgrade to a fixed version: Linux kernel 4.19.321, 5.10.225, 5.15.166, 5.4.283. Check the vendor advisory for mitigations.

References

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