CVE-2026-98573
Received Received - Intake

Buffer Underflow in Linux Kernel skbuff

Publication date: 2026-10-18

Last updated on: 2026-10-18

Assigner: kernel.org

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.

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Meta Information

Published
2026-10-18
Last Modified
2026-10-18
Generated
2026-10-18
AI Q&A
2026-10-18
EPSS Evaluated
N/A
NVD
CVE-2026-98573
EUVD
EUVD-2026-103618

Affected Vendors & Products

Showing 9 associated CPEs
Vendor Product Version / Range
Linux Linux 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3
Linux Linux 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3
Linux Linux 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3
Linux Linux 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3
Linux Linux 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3
Linux Linux 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3
Linux Linux 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3
Linux Linux 1431fb31ecbaba1b5718006128f0f2ed0b94e1c3
Linux Linux 3.13

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability is in the Linux kernel's network buffer handling. It involves a calculation error when processing IPv6 extension headers that could lead to a buffer underflow. Specifically, a function subtracts the wrong value during length checks, causing a negative length to be passed to a memory copy operation, potentially leading to memory corruption or crashes.

Impact Analysis

If exploited, this flaw could cause system crashes, denial-of-service conditions, or potential privilege escalation on affected Linux systems. It primarily affects network processing, so systems handling IPv6 traffic are most at risk.

Mitigation Strategies

Update the Linux kernel to a patched version that includes the fix for CVE-2026-98573. Monitor vendor advisories for kernel updates and apply them promptly.

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