CVE-2026-53012nexthop: fix IPv6 route referencing IPv4 nexthop
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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
- CVSS
- 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 7bf4796dd09984ad1612877a82d0d139c70ae27f before ceffe81a0be92afc0cd1340bc8ca46559cce9bb4; from 7bf4796dd09984ad1612877a82d0d139c70ae27f before 9c2d6770a5f4545a307eb66979bef7656a34d621; from 7bf4796dd09984ad1612877a82d0d139c70ae27f before 6275796f22bb382f3e9aa58ed0b4ef7bdad78cb8; from 7bf4796dd09984ad1612877a82d0d139c70ae27f before aaac3bed034239e1d75732211d9b05f30b0b4f35; from 7bf4796dd09984ad1612877a82d0d139c70ae27f before ad85961004fd4bd2f31209ac4b07612c6cefb9e7; from 7bf4796dd09984ad1612877a82d0d139c70ae27f before 613c8f4a501421dd258b07ea614205d4e16ec845; from 7bf4796dd09984ad1612877a82d0d139c70ae27f before b3b7e850e1541f0520c4a12ec884255c30427ff6; from 7bf4796dd09984ad1612877a82d0d139c70ae27f before 29c95185ba32b621fbc3800fb86e7dc3edf5c2be | CNA record |
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
linux linux_kernel linux:linux_kernel | from 5.3 before 5.10.258; from 5.11 before 5.15.209; from 5.16 before 6.1.175; from 6.2 before 6.6.141; from 6.7 before 6.12.91; from 6.13 before 6.18.33; from 6.19 before 7.0.10 | NVD |
References
- https://git.kernel.org/stable/c/ceffe81a0be92afc0cd1340bc8ca46559cce9bb4patch
- https://git.kernel.org/stable/c/9c2d6770a5f4545a307eb66979bef7656a34d621patch
- https://git.kernel.org/stable/c/6275796f22bb382f3e9aa58ed0b4ef7bdad78cb8patch
- https://git.kernel.org/stable/c/aaac3bed034239e1d75732211d9b05f30b0b4f35patch
- https://git.kernel.org/stable/c/ad85961004fd4bd2f31209ac4b07612c6cefb9e7patch
- https://git.kernel.org/stable/c/613c8f4a501421dd258b07ea614205d4e16ec845patch
- https://git.kernel.org/stable/c/b3b7e850e1541f0520c4a12ec884255c30427ff6patch
- https://git.kernel.org/stable/c/29c95185ba32b621fbc3800fb86e7dc3edf5c2bepatch
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
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.