Pull-bound underflow in Linux kernel IPv6 checksum setup
Key facts
- Attack vector
- —
- Privileges required
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- User interaction
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- Attack complexity
- —
- Impact type
- —
- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 7 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
The Linux kernel from 3.13 is affected. The skb_maybe_pull_tail() helper subtracts the linear header length from an unsigned bound without checking it, so while parsing IPv6 extension headers the bound can wrap and become a negative length. That negative length can then become a very large copy length, which is passed to a byte copy routine.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
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.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
Upgrade the Linux kernel to 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9 or 7.3, matching your stable branch. Red Hat lists Red Hat Enterprise Linux 7, 8, 9 and 10 and Red Hat OpenShift Container Platform 4 and 5 as affected with no fix available. Red Hat lists Red Hat Enterprise Linux 6 as affected with no plan given.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA Linux (Linux) Fixed in 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9, 7.3
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 6 | Affected | — |
| Red Hat Enterprise Linux 7 | Affected | No fix yet |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet |
Timeline
- 2026-10-18 Threatist record created from CVE-2026-98573
- 2026-10-18 Alias added: GHSA-23rj-wp7f-556g
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-20 Affected versions changed · Red Hat
- 2026-10-20 CVSS score added · Red Hat
- 2026-10-30 Affected versions changed · Red Hat
References
Other 8
- 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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Sources
- CVE-2026-98573 · CVE Program
- CVE-2026-98573 · NVD
- FIRST EPSS
- GHSA-23rj-wp7f-556g · GitHub Advisory Database · CC BY 4.0
- CVE-2026-98573 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences