netfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag
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.
CVE-2026-72250
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-72250
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "6e8cd710ca35c576f5f2e5a396047c9ac61f75e5",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "2a95ec21824a8ad81ad660b12231456fc0ac9830",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "bbcdef2061b170af45702ce6b359c02c12acfc94",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "cd0d7bbc027b4d3329712cdcdeb4e5567ffd0d58",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "53ef70a315420ed31581d38343684b3bf9a3c76d",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "a58230f3a7c4f6c3261786bc1efb72c42e68cd25",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "00bdce2fda7e430d24cfbc96764a1b96deb31f82",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "3b08fed5b7e0d5e3a25d73ef3ba09cd33ade16c9",
"versionType": "git"
}
],
"programFiles": [
"net/ipv6/netfilter/nf_conntrack_reasm.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.15"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.15",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.261",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.212",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/ipv6/netfilter/nf_conntrack_reasm.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-72250
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #32994 · Revision 1
- Added to Heist Feed
- Publisher date