CVE-2025-38377: debian linux Use-After-Free — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: rose: fix dangling neighbour pointers in rose_rt_device_down() There are two bugs in rose_rt_device_down() that can cause use-after-free: 1. The loop bound `t->count` is modified within the loop, which can cause the loop to terminate early and miss some entries. 2. When removing an entry from the neighbour array, the subsequent entries are moved up to fill the gap, but the loop index `i` is still incremented, causing the next entry to be skipped. For example, if a node has three neighbours (A, A, B) with count=3 and A is being removed, the second A is not checked. i=0: (A, A, B) -> (A, B) with count=2 ^ checked i=1: (A, B) -> (A, B) with count=2 ^ checked (B, not A!) i=2: (doesn't occur because i < count is false) This leaves the second A in the array with count=2, but the rose_neigh structure has been freed. Code that accesses these entries assumes that the first `count` entries are valid pointers, causing a use-after-free when it accesses the dangling pointer. Fix both issues by iterating over the array in reverse order with a fixed loop bound. This ensures that all entries are examined and that the removal of an entry doesn't affect subsequent iterations.

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CVSS v3.1 Score

7.8

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness Type (CWE)

CWE-416 Use After Free

Affected Products

Vendor	Product	Versions
linux	linux_kernel	2.6.13 — 5.4.296
linux	linux_kernel	5.5 — 5.10.240
linux	linux_kernel	5.11 — 5.15.187
linux	linux_kernel	5.16 — 6.1.144
linux	linux_kernel	6.2 — 6.6.97
linux	linux_kernel	6.7 — 6.12.37
linux	linux_kernel	6.13 — 6.15.6
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
debian	debian_linux	All

References

Advisories & Patches

https://git.kernel.org/stable/c/2b952dbb32fef835756f07ff0cd77efbb836dfea https://git.kernel.org/stable/c/2c6c82ee074bfcfd1bc978ec45bfea37703d840a https://git.kernel.org/stable/c/34a500caf48c47d5171f4aa1f237da39b07c6157 https://git.kernel.org/stable/c/446ac00b86be1670838e513b643933d78837d8db https://git.kernel.org/stable/c/7a1841c9609377e989ec41c16551309ce79c39e4 https://git.kernel.org/stable/c/94e0918e39039c47ddceb609500817f7266be756 https://git.kernel.org/stable/c/b6b232e16e08c6dc120672b4753392df0d28c1b4 https://git.kernel.org/stable/c/fe62a35fb1f77f494ed534fc69a9043dc5a30ce1

Other References

https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html

Frequently Asked Questions

What is CVE-2025-38377? +

In the Linux kernel, the following vulnerability has been resolved: rose: fix dangling neighbour pointers in rose_rt_device_down() There are two bugs in rose_rt_device_down() that can cause use-after-free: 1. The loop bound `t->count` is modified within the loop, which can cause the loop to terminate early and miss some entries. 2. When removing an entry from the neighbour array, the subsequent entries are moved up to fill the gap, but the loop index `i` is still incremented, causing the next entry to be skipped. For example, if a node has three neighbours (A, A, B) with count=3 and A is being removed, the second A is not checked. i=0: (A, A, B) -> (A, B) with count=2 ^ checked i=1: (A, B) -> (A, B) with count=2 ^ checked (B, not A!) i=2: (doesn't occur because i < count is false) This leaves the second A in the array with count=2, but the rose_neigh structure has been freed. Code that accesses these entries assumes that the first `count` entries are valid pointers, causing a use-after-free when it accesses the dangling pointer. Fix both issues by iterating over the array in reverse order with a fixed loop bound. This ensures that all entries are examined and that the removal of an entry doesn't affect subsequent iterations. It has a CVSS v3.1 base score of 7.8 (HIGH).

How severe is CVE-2025-38377? +

CVE-2025-38377 has a CVSS v3.1 score of 7.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-38377? +

CVE-2025-38377 affects products from debian, linux, specifically: debian_linux, linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-38377? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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