CVE-2026-98573 net: skbuff: fix pull-bound underflow in skb_checksum_setup_ipv6()
An integer underflow in the Linux kernel's IPv6 checksum setup allows remote attackers to cause memory corruption or denial of service via crafted packets.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98573?
CVE-2026-98573 is a vulnerability in Linux, published on 18 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-98573?
How do I fix CVE-2026-98573?
Apply the vendor's patch.
Is CVE-2026-98573 being exploited?
There is no known exploitation of CVE-2026-98573 in the wild and no public exploit code.
Sources
Also known as AZL-109367, BELL-CVE-2026-98573, DEBIAN-CVE-2026-98573, GHSA-23rj-wp7f-556g, UBUNTU-CVE-2026-98573.