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NVD / CVE Program· CNA Linux

CVE-2026-23300: net: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop

MediumCVSS 5.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.13% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 21ec92774d1536f71bdc90b0e3d052eff99cf093, 607e68c1b7c5a30c795571be1906d716e989a644, 8650db85b4259d2885d2a80fbc2317ce24194133; azl3 kernel 6.6.126.1-1 on Azure Linux 3.0 6.6.130.1-1.

Low priority for now. Upgrade to Linux Linux 21ec92774d1536f71bdc90b0e3d052eff99cf093, 607e68c1b7c5a30c795571be1906d716e989a644, 8650db85b4259d2885d2a80fbc2317ce24194133; azl3 kernel 6.6.126.1-1 on Azure Linux 3.0 6.6.130.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: net: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop When a standalone IPv6 nexthop object is created with a loopback device (e.g., "ip -6 nexthop add id 100 dev lo"), fib6_nh_init() misclassifies it as a reject route. This is because nexthop objects have no destination prefix (fc_dst=::), causing fib6_is_reject() to match any loopback nexthop. The reject path skips fib_nh_common_init(), leaving nhc_pcpu_rth_output unallocated. If an IPv4 route later references this nexthop, __mkroute_output() dereferences NULL nhc_pcpu_rth_output and panics. Simplify the check in fib6_nh_init() to only match explicit reject routes (RTF_REJECT) instead of using fib6_is_reject(). The loopback promotion heuristic in fib6_is_reject() is handled separately by ip6_route_info_create_nh(). After this change, the three cases behave as follows: 1. Explicit reject route ("ip -6 route add unreachable 2001:db8::/64"): RTF_REJECT is set, enters reject path, skips fib_nh_common_init(). No behavior change. 2. Implicit loopback reject route ("ip -6 route add 2001:db8::/32 dev lo"): RTF_REJECT is not set, takes normal path, fib_nh_common_init() is called. ip6_route_info_create_nh() still promotes it to reject afterward. nhc_pcpu_rth_output is allocated but unused, which is harmless. 3. Standalone nexthop object ("ip -6 nexthop add id 100 dev lo"): RTF_REJECT is not set, takes normal path, fib_nh_common_init() is called. nhc_pcpu_rth_output is properly allocated, fixing the crash when IPv4 routes reference this nexthop.

Published
Mar 25, 2026
Updated
Nov 10, 2026
EPSS
0.1% · 3th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 5.3affected
    • 493ced1ac47c48bb86d9d4e8e87df8592be85a0e and later · before 607e68c1b7c5a30c795571be1906d716e989a644affected · git
    • 493ced1ac47c48bb86d9d4e8e87df8592be85a0e and later · before c11d7c56c2076ee9cd72004f1976fe0734df2ae9affected · git
    • 493ced1ac47c48bb86d9d4e8e87df8592be85a0e and later · before b5062fc2150614c9ea8a611c2e0cb6e047ebfa3aaffected · git
    • 493ced1ac47c48bb86d9d4e8e87df8592be85a0e and later · before b299121e7453d23faddf464087dff513a495b4fcaffected · git
    • 493ced1ac47c48bb86d9d4e8e87df8592be85a0e and later · before f7c9f8e3607440fe39300efbaf46cf7b5eecb23faffected · git
    • 493ced1ac47c48bb86d9d4e8e87df8592be85a0e and later · before b3b5a037d520afe3d5276e653bc0ff516bbda34caffected · git
    • 493ced1ac47c48bb86d9d4e8e87df8592be85a0e and later · before 8650db85b4259d2885d2a80fbc2317ce24194133affected · git
    • 493ced1ac47c48bb86d9d4e8e87df8592be85a0e and later · before 21ec92774d1536f71bdc90b0e3d052eff99cf093affected · git
    • before 5.3not affected · semver
Affected versions · NVD (8)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.3 and later · before 5.10.253
  • linux linux kernel5.11 and later · before 5.15.203
  • linux linux kernel5.16 and later · before 6.1.167
  • linux linux kernel6.2 and later · before 6.6.130
  • linux linux kernel6.7 and later · before 6.12.77
  • linux linux kernel6.13 and later · before 6.18.17
  • linux linux kernel6.19 and later · before 6.19.7
  • linux linux kernel7.0

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.19.8-16.19.8-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe…KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-23298Mar 25, 2026 · can: ucan: Fix infinite loop from zero-length messages
    22Monitor
  • ← EarlierCVE-2026-23299Mar 25, 2026 · Bluetooth: purge error queues in socket destructors
    22Monitor
  • Later →CVE-2026-23302Mar 25, 2026 · net: annotate data-races around sk->sk_{data_ready,write_space}
    18Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux21ec92774d1536f71bdc90b0e3d052eff99cf093Vendor (CNA)
Linux Linux607e68c1b7c5a30c795571be1906d716e989a644Vendor (CNA)
Linux Linux8650db85b4259d2885d2a80fbc2317ce24194133Vendor (CNA)
Linux Linuxb299121e7453d23faddf464087dff513a495b4fcVendor (CNA)
Linux Linuxb3b5a037d520afe3d5276e653bc0ff516bbda34cVendor (CNA)
Linux Linuxb5062fc2150614c9ea8a611c2e0cb6e047ebfa3aVendor (CNA)
Linux Linuxc11d7c56c2076ee9cd72004f1976fe0734df2ae9Vendor (CNA)
Linux Linuxf7c9f8e3607440fe39300efbaf46cf7b5eecb23fVendor (CNA)
azl3 kernel 6.6.126.1-1 on Azure Linux 3.06.6.130.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.170-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (11 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records