nexthop: fix IPv6 route referencing IPv4 nexthop
In the Linux kernel, the following vulnerability has been resolved: nexthop: fix IPv6 route referencing IPv4 nexthop syzbot reported a panic [1] [2]. When an IPv6 nexthop is replaced with an IPv4 nexthop, the has_v4 flag of all groups containing this nexthop is not updated. This is because nh_group_v4_update is only called when replacing AF_INET to AF_INET6, but the reverse direction (AF_INET6 to AF_INET) is missed. This allows a stale has_v4=false to bypass fib6_check_nexthop, causing IPv6 routes to be attached to groups that effectively contain only AF_INET members. Subsequent route lookups then call nexthop_fib6_nh() which returns NULL for the AF_INET member, leading to a NULL pointer dereference. Fix by calling nh_group_v4_update whenever the family changes, not just AF_INET to AF_INET6. Reproducer: # AF_INET6 blackhole ip -6 nexthop add id 1 blackhole # group with has_v4=false ip nexthop add id 100 group 1 # replace with AF_INET (no -6), has_v4 stays false ip nexthop replace id 1 blackhole # pass stale has_v4 check ip -6 route add 2001:db8::/64 nhid 100 # panic ping -6 2001:db8::1 [1] https://syzkaller.appspot.com/bug?id=e17283eb2f8dcf3dd9b47fe6f67a95f71faadad0 [2] https://syzkaller.appspot.com/bug?id=8699b6ae54c9f35837d925686208402949e12ef3
CVE-2026-53012
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-2026-53012
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": "7bf4796dd09984ad1612877a82d0d139c70ae27f",
"lessThan": "ceffe81a0be92afc0cd1340bc8ca46559cce9bb4",
"versionType": "git"
},
{
"status": "affected",
"version": "7bf4796dd09984ad1612877a82d0d139c70ae27f",
"lessThan": "9c2d6770a5f4545a307eb66979bef7656a34d621",
"versionType": "git"
},
{
"status": "affected",
"version": "7bf4796dd09984ad1612877a82d0d139c70ae27f",
"lessThan": "6275796f22bb382f3e9aa58ed0b4ef7bdad78cb8",
"versionType": "git"
},
{
"status": "affected",
"version": "7bf4796dd09984ad1612877a82d0d139c70ae27f",
"lessThan": "aaac3bed034239e1d75732211d9b05f30b0b4f35",
"versionType": "git"
},
{
"status": "affected",
"version": "7bf4796dd09984ad1612877a82d0d139c70ae27f",
"lessThan": "ad85961004fd4bd2f31209ac4b07612c6cefb9e7",
"versionType": "git"
},
{
"status": "affected",
"version": "7bf4796dd09984ad1612877a82d0d139c70ae27f",
"lessThan": "613c8f4a501421dd258b07ea614205d4e16ec845",
"versionType": "git"
},
{
"status": "affected",
"version": "7bf4796dd09984ad1612877a82d0d139c70ae27f",
"lessThan": "b3b7e850e1541f0520c4a12ec884255c30427ff6",
"versionType": "git"
},
{
"status": "affected",
"version": "7bf4796dd09984ad1612877a82d0d139c70ae27f",
"lessThan": "29c95185ba32b621fbc3800fb86e7dc3edf5c2be",
"versionType": "git"
}
],
"programFiles": [
"net/ipv4/nexthop.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.3"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.3",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.258",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.209",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.175",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.141",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.91",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.33",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.10",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/ipv4/nexthop.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-53012
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #28425 · Revision 1
- Added to Heist Feed
- Publisher date