CVE-2025-39717
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-09-05

Last updated on: 2025-11-25

Assigner: kernel.org

Description
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.
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Meta Information
Published
2025-09-05
Last Modified
2025-11-25
Generated
2026-05-07
AI Q&A
2025-09-05
EPSS Evaluated
2026-05-05
NVD
CVE-2025-39717
Affected Vendors & Products
Showing 3 associated CPEs
Vendor Product Version / Range
linux linux_kernel 6.17
linux linux_kernel 6.17
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-416 The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability in the Linux kernel involves the open_tree_attr function, which was supposed to prevent changes to id-mappings without the OPEN_TREE_CLONE flag. Due to a bug, users could bypass this restriction by calling open_tree_attr without OPEN_TREE_CLONE, allowing id-mapping changes on detached mounts. This could lead to use-after-free (UAF) and locking issues, potentially causing unintended behavior or security risks.


How can this vulnerability impact me? :

The vulnerability allows modification of id-mappings on detached mounts, which can cause use-after-free and locking issues. This could lead to system instability, security risks such as privilege escalation, or unauthorized access due to improper handling of mount namespaces and id-mappings.


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