CVE-2026-98573

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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EPSS — Exploit Prediction

0.0022

Probability of exploitation

0.12%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

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

Frequently Asked Questions

What is CVE-2026-98573? +

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.

How do I check if I'm vulnerable to CVE-2026-98573? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.