# CVE-2025-38708: Linux Kernel use after free in DRBD handle_write_conflicts

Source: https://junglewise.ai/threats/cve-2025-38708-linux-kernel-use-after-free-in-drbd-handle-write-conflicts  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2025-09-04. Updated: 2026-07-30  
License: CC BY 4.0 with a link back

CVE-2025-38708 · Severity: critical · CVSS 9.8 · Published 2025-09-04

A vulnerability exists in the Linux kernel's Distributed Replicated Block Device (DRBD) driver, which is used to mirror storage between servers for high availability. Under specific configurations where two servers are allowed to write simultaneously, a software error can cause the system to crash or allow unauthorized memory access. This could lead to service outages or potential data corruption in environments using older DRBD versions for clustered storage or live virtual machine migration.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel), [Siemens SIMATIC CN 4100](https://junglewise.ai/threats/technologies/simatic-cn-4100), [Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP](https://junglewise.ai/threats/technologies/simatic-s7-1500-cpu-1518-4-pn-dp-mfp). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux), [Siemens](https://junglewise.ai/threats/vendors/siemens).

## Quick answers

**Is CVE-2025-38708 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-38708 being exploited in the wild.

**How severe is CVE-2025-38708?** Critical severity, with a CVSS score of 9.8, published 4 September 2025.

**Which products and versions are affected?** Linux Kernel 4.5 to 5.4.297, 5.5 to 5.10.241, 5.11 to 5.15.190, 5.16 to 6.1.149, 6.2 to 6.6.103, 6.7 to 6.12.43, 6.13 to 6.15.11, 6.16 to 6.16.2, versions prior to 6.15 (stable branches 4.19.y, 5.4.y, 5.10.y, 5.15.y, 6.1.y, 6.6.y, 6.10.y, 6.11.y); Siemens SIMATIC CN 4100 versions prior to V5.0; Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5 and later.

**Is there a fix for CVE-2025-38708?** A patch was published on 2025-06-27: Initial patch authored Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2025-38708 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2025-38708?** Check whether you run Linux Kernel, Siemens SIMATIC CN 4100 or Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A use-after-free (UAF) vulnerability exists in the Linux kernel DRBD driver (drivers/block/drbd/drbd_receiver.c) due to a missing reference count increment (kref_get) in the 'handle_write_conflicts' function. When the 'two-primaries' feature is enabled and concurrent writes occur, the driver may prematurely call 'drbd_destroy_device', leading to a UAF condition and subsequent kernel panic. While the vendor notes this path is rarely triggered in production due to upper-layer locking (DLM), an attacker capable of generating specific network-based write conflicts could trigger the flaw. Patches have been released for multiple stable kernel branches including 4.19, 5.4, 5.10, 5.15, 6.1, 6.6, 6.10, and 6.11.

## Affected products

- Linux Linux Kernel versions prior to 6.15 (stable branches 4.19.y, 5.4.y, 5.10.y, 5.15.y, 6.1.y, 6.6.y, 6.10.y, 6.11.y)
- Siemens SIMATIC CN 4100 versions prior to V5.0
- Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP V3.1.5 and later

## Timeline

- 2025-06-27: patched: Initial patch authored
- 2025-09-04: advisory: CVE-2025-38708 published

## References

- [https://git.kernel.org/stable/c/00c9c9628b49e368d140cfa61d7df9b8922ec2a8](https://git.kernel.org/stable/c/00c9c9628b49e368d140cfa61d7df9b8922ec2a8)
- [https://git.kernel.org/stable/c/0336bfe9c237476bd7c45605a36ca79c2bca62e5](https://git.kernel.org/stable/c/0336bfe9c237476bd7c45605a36ca79c2bca62e5)
- [https://git.kernel.org/stable/c/3a896498f6f577e57bf26aaa93b48c22b6d20c20](https://git.kernel.org/stable/c/3a896498f6f577e57bf26aaa93b48c22b6d20c20)
- [https://git.kernel.org/stable/c/46e3763dcae0ffcf8fcfaff4fc10a90a92ffdd89](https://git.kernel.org/stable/c/46e3763dcae0ffcf8fcfaff4fc10a90a92ffdd89)
- [https://git.kernel.org/stable/c/57418de35420cedab035aa1da8a26c0499b7f575](https://git.kernel.org/stable/c/57418de35420cedab035aa1da8a26c0499b7f575)
- [https://git.kernel.org/stable/c/7d483ad300fc0a06f69b019dda8f74970714baf8](https://git.kernel.org/stable/c/7d483ad300fc0a06f69b019dda8f74970714baf8)
- [https://git.kernel.org/stable/c/810cd546a29bfac90ed1328ea01d693d4bd11cb1](https://git.kernel.org/stable/c/810cd546a29bfac90ed1328ea01d693d4bd11cb1)

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