High 7.8Published Aug 15, 2026

CVE-2026-72250netfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag

Updated under an hour ago (Oct 27, 2026, 12:20 PM ET)

This data is behind schedule: last updated Oct 27, 2026, 10:23 AM ET. We are working on it.Behind: National Vulnerability Database (CVE API 2.0, CPE API 2.0).

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag nf_ct_frag6_reasm() slides the packet head forward to drop the IPv6 fragment header and then unconditionally advances skb->mac_header: skb->mac_header += sizeof(struct frag_hdr); On the NF_INET_LOCAL_OUT defrag path the skb has no link-layer header yet, so skb->mac_header is still the "not set" sentinel (u16)~0U. Adding sizeof(struct frag_hdr) wraps it to a small value (0xffff + 8 == 7), after which skb_mac_header_was_set() wrongly reports a MAC header is present and skb_mac_header() points into the headroom. The reassembler has done this unconditional add since it was introduced; it was harmless while mac_header was a bare pointer, but wrong once mac_header became a u16 offset whose unset state is the ~0U sentinel tested by skb_mac_header_was_set(). The sibling net/ipv6/reassembly.c does the same relocation and does guard the adjustment; mirror the guard here.

CVSS: 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Received
Record last updated: Oct 16, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 builds before 6e8cd710ca35c576f5f2e5a396047c9ac61f75e5; 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 builds before 2a95ec21824a8ad81ad660b12231456fc0ac9830; from 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 before bbcdef2061b170af45702ce6b359c02c12acfc94; from 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 before cd0d7bbc027b4d3329712cdcdeb4e5567ffd0d58; from 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 before 53ef70a315420ed31581d38343684b3bf9a3c76d; from 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 before a58230f3a7c4f6c3261786bc1efb72c42e68cd25; 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 builds before 00bdce2fda7e430d24cfbc96764a1b96deb31f82; 9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1 builds before 3b08fed5b7e0d5e3a25d73ef3ba09cd33ade16c9	CNA record

References

References

https://git.kernel.org/stable/c/6e8cd710ca35c576f5f2e5a396047c9ac61f75e5
https://git.kernel.org/stable/c/2a95ec21824a8ad81ad660b12231456fc0ac9830
https://git.kernel.org/stable/c/bbcdef2061b170af45702ce6b359c02c12acfc94
https://git.kernel.org/stable/c/cd0d7bbc027b4d3329712cdcdeb4e5567ffd0d58
https://git.kernel.org/stable/c/53ef70a315420ed31581d38343684b3bf9a3c76d
https://git.kernel.org/stable/c/a58230f3a7c4f6c3261786bc1efb72c42e68cd25
https://git.kernel.org/stable/c/00bdce2fda7e430d24cfbc96764a1b96deb31f82
https://git.kernel.org/stable/c/3b08fed5b7e0d5e3a25d73ef3ba09cd33ade16c9

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.