CVE Catalog

CVE-2025-39717

HighCVSS 7.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.14%

4th percentile - higher than 4% of all known CVEs

Summary

In the Linux kernel, a vulnerability was found in the open_tree_attr(2) function that allowed changing idmappings for a mounted filesystem without using the OPEN_TREE_CLONE flag. This bypass could lead to security issues such as use-after-free (UAF) and locking problems.

Risk Assessment

An attacker could change idmappings for visible but detached mount points, potentially leading to privilege escalation or data integrity violations.

Recommendation

It is recommended to immediately update the Linux kernel to a version containing the fix that enforces the use of OPEN_TREE_CLONE when changing idmappings.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: open_tree_attr: do not allow id-mapping changes without OPEN_TREE_CLONE As described in commit 7a54947e727b ('Merge patch series "fs: allow changing idmappings"'), open_tree_attr(2) was necessary in order to allow for a detached mount to be created and have its idmappings changed without the risk of any racing threads operating on it. For this reason, mount_setattr(2) still does not allow for id-mappings to be changed. However, there was a bug in commit 2462651ffa76 ("fs: allow changing idmappings") which allowed users to bypass this restriction by calling open_tree_attr(2) *without* OPEN_TREE_CLONE. can_idmap_mount() prevented this bug from allowing an attached mountpoint's id-mapping from being modified (thanks to an is_anon_ns() check), but this still allows for detached (but visible) mounts to have their be id-mapping changed. This risks the same UAF and locking issues as described in the merge commit, and was likely unintentional.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS