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

5.5 CVSS

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).

Classification

CVE ID: CVE-2024-44947

CVSS Base Severity: MEDIUM

CVSS Base Score: 5.5

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

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.76% (probability of being exploited)

EPSS Percentile: 72.33% (scored less or equal to compared to others)

EPSS Date: 2025-06-02 (when was this score calculated)

Stakeholder-Specific Vulnerability Categorization (SSVC)

SSVC Exploitation: none

SSVC Technical Impact: partial

SSVC Automatable: false

References

https://nvd.nist.gov/vuln/detail/CVE-2024-44947
https://git.kernel.org/stable/c/49934861514d36d0995be8e81bb3312a499d8d9a
https://git.kernel.org/stable/c/33168db352c7b56ae18aa55c2cae1a1c5905d30e
https://git.kernel.org/stable/c/4690e2171f651e2b415e3941ce17f2f7b813aff6
https://git.kernel.org/stable/c/8c78303eafbf85a728dd84d1750e89240c677dd9
https://git.kernel.org/stable/c/831433527773e665bdb635ab5783d0b95d1246f4
https://git.kernel.org/stable/c/ac42e0f0eb66af966015ee33fd355bc6f5d80cd6
https://git.kernel.org/stable/c/18a067240817bee8a9360539af5d79a4bf5398a5
https://git.kernel.org/stable/c/3c0da3d163eb32f1f91891efaade027fa9b245b9
https://project-zero.issues.chromium.org/issues/42451729

Timeline