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.