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Back to active CVEs
Medium · CVSS 5.5CVE-2026-53012

nexthop: fix IPv6 route referencing IPv4 nexthopCVE-2026-53012

Answer in brief

CVE-2026-53012 records a Medium severity (CVSS 5.5) vulnerability in nexthop: fix IPv6 route referencing IPv4 nexthop. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jun 24, 2026Updated Oct 15, 2026Source checked Oct 23, 2026First seen by HOL Jun 24, 2026Material review Oct 15, 2026
Upstream Advisory

Key facts

Risk
Medium · CVSS 5.5
Exploitation
Not marked as known exploited
Affected software
9 mapped packages or products
Fix availability
Available

Why this deserves its current priority

CVSS is 5.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.

Affected products and reported versions
ProductAffected versionsFixed versions
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*Not reportedNot reported
Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Linux/Linuxgeneric>=7bf4796dd09984ad1612877a82d0d139c70ae27f <ceffe81a0be92afc0cd1340bc8ca46559cce9bb4 || >=7bf4796dd09984ad1612877a82d0d139c70ae27f <9c2d6770a5f4545a307eb66979bef7656a34d621 || >=7bf4796dd09984ad1612877a82d0d139c70ae27f <6275796f22bb382f3e9aa58ed0b4ef7bdad78cb8 || >=7bf4796dd09984ad1612877a82d0d139c70ae27f <aaac3bed034239e1d75732211d9b05f30b0b4f35 || >=7bf4796dd09984ad1612877a82d0d139c70ae27f <ad85961004fd4bd2f31209ac4b07612c6cefb9e7 || >=7bf4796dd09984ad1612877a82d0d139c70ae27f <613c8f4a501421dd258b07ea614205d4e16ec845 || >=7bf4796dd09984ad1612877a82d0d139c70ae27f <b3b7e850e1541f0520c4a12ec884255c30427ff6 || >=7bf4796dd09984ad1612877a82d0d139c70ae27f <29c95185ba32b621fbc3800fb86e7dc3edf5c2beceffe81a0be92afc0cd1340bc8ca46559cce9bb4, 9c2d6770a5f4545a307eb66979bef7656a34d621, 6275796f22bb382f3e9aa58ed0b4ef7bdad78cb8, aaac3bed034239e1d75732211d9b05f30b0b4f35, ad85961004fd4bd2f31209ac4b07612c6cefb9e7, 613c8f4a501421dd258b07ea614205d4e16ec845, b3b7e850e1541f0520c4a12ec884255c30427ff6, 29c95185ba32b621fbc3800fb86e7dc3edf5c2be
Linux/Linuxgeneric5.3Not reported
Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.6 <**
Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.7 <**
Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric>=V3.1.6 <**
Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric>=V3.1.7 <**
Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.6 <**
Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.7 <**

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux, Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP.
  2. 2Review the reported fix. Update Linux/Linux to ceffe81a0be92afc0cd1340bc8ca46559cce9bb4; Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to *; Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to * if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Jun 24, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Oct 15, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Jun 24, 2026

Sources and claim methodology

  • Source referencecert-portal.siemens.com
  • Source referencecert-portal.siemens.com
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
Upstream source description

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

Quoted source text, attributed separately from HOL analysis.

Record context

Vulnerability class
Vulnerability
EPSS
Not reported
CWE IDs
CWE-476
Source
CVE List V5
Source checked
Oct 23, 2026
References
10 linked sources
Open source record