# CVE-2025-39827

## Summary

- **CVE ID:** CVE-2025-39827
- **Severity:** HIGH
- **CVSS Score:** 8.8 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Sep 16, 2025
- **Last Modified:** Sep 8, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:

net: rose: include node references in rose_neigh refcount

Current implementation maintains two separate reference counting
mechanisms: the 'count' field in struct rose_neigh tracks references from
rose_node structures, while the 'use' field (now refcount_t) tracks
references from rose_sock.

This patch merges these two reference counting systems using 'use' field
for proper reference management. Specifically, this patch adds incrementing
and decrementing of rose_neigh->use when rose_neigh->count is incremented
or decremented.

This patch also modifies rose_rt_free(), rose_rt_device_down() and
rose_clear_route() to properly release references to rose_neigh objects
before freeing a rose_node through rose_remove_node().

These changes ensure rose_neigh structures are properly freed only when
all references, including those from rose_node structures, are released.
As a result, this resolves a slab-use-after-free issue reported by Syzbot.

## Affected Products

- Linux — Linux (1da177e4c3f41524e886b7f1b8a0c1fc7321cac2)
- Linux — Linux (2.6.12)
- Linux — Linux (0)
- Linux — Linux (6.1.150)
- Linux — Linux (6.6.104)
- Linux — Linux (6.12.45)
- Linux — Linux (6.16.5)
- Linux — Linux (6.17)

## References

- [CNA](https://git.kernel.org/stable/c/4cce478c3e82a5fc788d72adb2f4c4e983997639)
- [CNA](https://git.kernel.org/stable/c/9c547c8eee9d1cf6e744611d688b9f725cf9a115)
- [CNA](https://git.kernel.org/stable/c/d7563b456ed44151e1a82091d96f60166daea89b)
- [CNA](https://git.kernel.org/stable/c/384210cceb1873a4c8218b27ba0745444436b728)
- [CNA](https://git.kernel.org/stable/c/da9c9c877597170b929a6121a68dcd3dd9a80f45)
- [CVE](https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-032379.html)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-019113.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.21%
- **EPSS Percentile:** 11.5

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._