CVE-2025-38708
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-09-04

Last updated on: 2026-03-17

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: drbd: add missing kref_get in handle_write_conflicts With `two-primaries` enabled, DRBD tries to detect "concurrent" writes and handle write conflicts, so that even if you write to the same sector simultaneously on both nodes, they end up with the identical data once the writes are completed. In handling "superseeded" writes, we forgot a kref_get, resulting in a premature drbd_destroy_device and use after free, and further to kernel crashes with symptoms. Relevance: No one should use DRBD as a random data generator, and apparently all users of "two-primaries" handle concurrent writes correctly on layer up. That is cluster file systems use some distributed lock manager, and live migration in virtualization environments stops writes on one node before starting writes on the other node. Which means that other than for "test cases", this code path is never taken in real life. FYI, in DRBD 9, things are handled differently nowadays. We still detect "write conflicts", but no longer try to be smart about them. We decided to disconnect hard instead: upper layers must not submit concurrent writes. If they do, that's their fault.
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Meta Information
Published
2025-09-04
Last Modified
2026-03-17
Generated
2026-05-07
AI Q&A
2025-09-04
EPSS Evaluated
2026-05-05
NVD
CVE-2025-38708
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
linux kernel 6.1.153
linux kernel 5.10.244
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability is in the Linux kernel's DRBD component when 'two-primaries' mode is enabled. DRBD tries to handle concurrent writes to the same sector on both nodes to ensure data consistency. However, a missing reference count increment (kref_get) in handling write conflicts causes a premature destruction of a device object (drbd_destroy_device), leading to use-after-free errors and kernel crashes.


How can this vulnerability impact me? :

If triggered, this vulnerability can cause kernel crashes due to use-after-free errors in DRBD when concurrent writes occur in 'two-primaries' mode. However, in real-life scenarios, this code path is rarely taken because cluster file systems use distributed lock managers and virtualization environments prevent concurrent writes on both nodes. Therefore, the practical impact is limited mainly to test cases or misconfigured environments.


What immediate steps should I take to mitigate this vulnerability?

To mitigate this vulnerability, ensure that you are not using DRBD with the 'two-primaries' feature enabled in scenarios that allow concurrent writes without proper distributed lock management. Avoid using DRBD as a random data generator or in test cases that trigger this code path. Upgrade to DRBD 9 or later, where write conflicts are handled differently by disconnecting hard instead of attempting to handle concurrent writes internally. Additionally, ensure that upper layers do not submit concurrent writes to DRBD.


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