Linux Kernel up to 7.0-rc2 net fib6_nh_init null pointer dereference

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Summaryinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 7.0-rc2. This vulnerability affects the function fib6_nh_init of the component net. Executing a manipulation can lead to null pointer dereference. This vulnerability is handled as CVE-2026-23300. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 7.0-rc2. This vulnerability affects the function fib6_nh_init of the component net. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2026-23300 since 01/13/2026. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 303725 (Linux Distros Unpatched Vulnerability : CVE-2026-23300), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.167, 6.6.130, 6.12.77, 6.18.17, 6.19.7 or 7.0-rc3 eliminates this vulnerability. Applying the patch b5062fc2150614c9ea8a611c2e0cb6e047ebfa3a/b299121e7453d23faddf464087dff513a495b4fc/f7c9f8e3607440fe39300efbaf46cf7b5eecb23f/b3b5a037d520afe3d5276e653bc0ff516bbda34c/8650db85b4259d2885d2a80fbc2317ce24194133/21ec92774d1536f71bdc90b0e3d052eff99cf093 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (303725) and CERT Bund (WID-SEC-2026-0861). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Open Source Linux Kernel

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.1.166
• 6.6.129
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
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• 6.12.70
• 6.12.71
• 6.12.72
• 6.12.73
• 6.12.74
• 6.12.75
• 6.12.76
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3
• 6.19.4
• 6.19.5
• 6.19.6
• 7.0-rc1
• 7.0-rc2

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.7
VulDB Meta Temp Score: 5.5

VulDB Base Score: 5.7
VulDB Temp Score: 5.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 303725
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-23300

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.167/6.6.130/6.12.77/6.18.17/6.19.7/7.0-rc3
Patch: b5062fc2150614c9ea8a611c2e0cb6e047ebfa3a/b299121e7453d23faddf464087dff513a495b4fc/f7c9f8e3607440fe39300efbaf46cf7b5eecb23f/b3b5a037d520afe3d5276e653bc0ff516bbda34c/8650db85b4259d2885d2a80fbc2317ce24194133/21ec92774d1536f71bdc90b0e3d052eff99cf093

Timelineinfo

01/13/2026 CVE reserved
03/25/2026 +71 days Advisory disclosed
03/25/2026 +0 days VulDB entry created
03/30/2026 +4 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-23300 (🔒)
GCVE (CVE): GCVE-0-2026-23300
GCVE (VulDB): GCVE-100-353026
CERT Bund: WID-SEC-2026-0861 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 03/25/2026 12:54
Updated: 03/30/2026 00:43
Changes: 03/25/2026 12:54 (59), 03/26/2026 04:55 (7), 03/26/2026 07:59 (2), 03/30/2026 00:43 (1)
Complete: 🔍
Cache ID: 216:584:103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Discussion

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