Skip to main content

Linux Kernel EUVDEUVD-2026-21948

| CVE-2026-31424 MEDIUM
NULL Pointer Dereference (CWE-476)
2026-04-13 Linux
Denial Of Service Linux Null Pointer Dereference Canonical
5.5
CVSS 3.1 · NVD
View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain local access with CAP_NET_ADMIN
  2. Delivery
    Load NFPROTO_UNSPEC xt_match into ARP chain via nft_compat
  3. Exploit
    Trigger ARP output traffic on affected interface
  4. Execution
    Kernel evaluates rule; dereferences NULL state->in pointer
  5. Impact
    Kernel panic crashes system

Vulnerability Assessment

Weakness
CWE
CWE-476
OWASP Top 10:2025
A10:2025 - Mishandling of Exceptional Conditions
ASVS 5.0
V16 - Security Logging and Error Handling Null pointer safety, defensive checks
MITRE ATT&CK

1 technique across 1 tactic: Impact

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Sign in to read
Exploitation Conditions

Exploitation requires a local attacker with CAP_NET_ADMIN privileges or access to a user namespace with sufficient network capabilities to load nftables rules. The specific trigger is loading an NFPROTO_UNSPEC-registered xt_match or xt_target (such as xt_devgroup) into an ARP nftables chain via nft_compat, then causing ARP output traffic to traverse that hook. This requires: (1) CAP_NET_ADMIN or an unprivileged user namespace with network capabilities; (2) CONFIG_NFT_COMPAT compiled into the running kernel; (3) a network interface that processes ARP traffic; (4) the attacker-controlled rule to target the ARP output or forward chain with an incompatible NFPROTO_UNSPEC extension whose .hooks bitmask includes value 1. Exploitation is not possible remotely - AV:L is confirmed by the CVSS vector. Environments without nft_compat, without ARP-capable interfaces, or where CAP_NET_ADMIN is strictly restricted to root are not practically exploitable.
Impact

CVSS 5.5 with AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H is consistent with the technical description: local access, low complexity, low privileges (CAP_NET_ADMIN or equivalent), no user interaction, and impact limited entirely to availability. There is no confidentiality or integrity impact. EPSS at 0.02% (7th percentile) aligns with the local attack vector and the specialized prerequisite of loading custom ARP netfilter rules via nft_compat - this is not a mass-exploitation scenario. The CVE is not in CISA KEV and no public POC has been identified at time of analysis. Real-world risk is concentrated in multi-tenant and containerized environments (e.g., cloud VMs, Kubernetes nodes, LXC/Docker with delegated CAP_NET_ADMIN) where untrusted workloads can configure netfilter rules; in such environments this is a local denial-of-service that can crash the entire host. For standard single-tenant servers or desktops requiring root to load netfilter rules, practical risk is low. No conflicts between CVSS signals and description were identified; the local vector is consistent with the CAP_NET_ADMIN requirement.
Exploit ScenarioDerived

An attacker with local shell access and CAP_NET_ADMIN on a Linux host (or inside a container with delegated network capabilities) uses nft_compat to load a netfilter rule applying the xt_devgroup match - an NFPROTO_UNSPEC extension - to an ARP output chain. When the host subsequently sends or forwards ARP traffic, the kernel evaluates the rule on the ARP output hook, dereferences state->in which is NULL in that context, and panics with a general protection fault, crashing the entire system. No public POC has been identified, but the detailed kernel oops trace and call chain (devgroup_mt → nft_match_eval → nft_do_chain_arp → nf_hook_slow → arp_xmit) embedded in the CVE description provides sufficient technical detail to reconstruct the trigger condition.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.0% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAIv1 – May 20, 2026

NULL pointer dereference in the Linux kernel's netfilter x_tables subsystem allows a local attacker with CAP_NET_ADMIN privileges to crash the system by loading an NFPROTO_UNSPEC-registered xt_match or xt_target (e.g., xt_devgroup) into an ARP nftables chain via nft_compat, triggering a kernel panic and complete availability loss. CVSS 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H) accurately reflects the local-only, availability-only impact, and EPSS at 0.02% (7th percentile) indicates very low real-world exploitation probability. No active exploitation confirmed (not in CISA KEV); vendor-released patches are available across multiple stable kernel branches.

RemediationAI

Upgrade to a patched kernel release: 6.1.168 or later for the 6.1.x LTS branch, 6.6.134 or later for the 6.6.x LTS branch, 6.12.81 or later for 6.12.x, 6.18.22 or later for 6.18.x, 6.19.12 or later for 6.19.x, or kernel 7.0 or later. Stable-branch patches are available at https://git.kernel.org/stable/c/1cd6313c8644bfebbd813a05da9daa21b09dd68c and the related commits listed above; canonical distribution packages (Ubuntu, Debian, RHEL) should be monitored for backported security updates. Where immediate patching is not possible, restrict CAP_NET_ADMIN delegation to trusted processes only - on systems running containers, set kernel.unprivileged_userns_clone=0 (Debian/Ubuntu sysctl) or equivalent seccomp/AppArmor profiles to prevent unprivileged users from obtaining network-capable namespaces; note this may break legitimate containerized workloads that rely on user namespaces for networking. Additionally, if ARP processing through custom nftables chains is not required, disabling CONFIG_NFT_COMPAT at build time eliminates the attack surface entirely, though this is only practical for custom kernel builds. NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2026-31424.

Affected VersionsENISA

Linux 9291747f118d6404e509747b85ff5f6dfec368d2 <3d5d488f11776738deab9da336038add95d342d1
Linux patch: 6.12.81
Linux 9291747f118d6404e509747b85ff5f6dfec368d2 <f00ac65c90ea475719e08d629e2e26c8b4e6999b
Linux 2.6.39
Linux patch: 6.6.134
Linux patch: 6.18.22
Linux 9291747f118d6404e509747b85ff5f6dfec368d2 <e7e1b6bcb389c8708003d40613a59ff2496f6b1f
Linux patch: 6.19.12
Linux patch: 7.0
Linux patch: 6.1.168
Linux 9291747f118d6404e509747b85ff5f6dfec368d2 <1cd6313c8644bfebbd813a05da9daa21b09dd68c
Linux 9291747f118d6404e509747b85ff5f6dfec368d2 <dc3e27dd7d76e21106b8f9bbdc31f5da74a89014
Linux 9291747f118d6404e509747b85ff5f6dfec368d2 <3e79374b03bf9a2f282f0eb1d0ac3776f7e0f28a
Linux patch: 0

Affected Packages

euvd linux no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Sign in to check
Technical ContextAI · show details

The Linux kernel netfilter subsystem allows xt_match and xt_target structs registered with NFPROTO_UNSPEC to be loaded by any protocol family through the nft_compat interface. These structs use a .hooks bitmask with NF_INET_* constants to restrict which netfilter hooks they may execute on - a layout shared by IPv4, IPv6, INET, and bridge (all defining the same five hooks: PRE_ROUTING=0 through POST_ROUTING=4). ARP, however, defines only three hooks with semantically different assignments: NF_ARP_IN=0, NF_ARP_OUT=1, NF_ARP_FORWARD=2. The critical flaw is that NF_ARP_OUT (value 1) numerically aliases NF_INET_LOCAL_IN (also value 1), causing xt_check_match/xt_check_target to incorrectly pass the .hooks validation for NFPROTO_ARP. This allows extensions like xt_devgroup - which assumes state->in is populated on input hooks - to execute on ARP output chains where state->in is NULL, producing a NULL pointer dereference (CWE-476) and kernel panic. The affected CPE is cpe:2.3:a:linux:linux:*:*:*:*:*:*:*:* with the vulnerability introduced at commit 9291747f118d6404e509747b85ff5f6dfec368d2 (Linux 2.6.39).

Know when Canonical gets its next vulnerability

  • Watch products and get an email when something new is published
  • Check this CVE against your own stack and servers
  • Exploit and PoC references, threat intelligence from 22 sources
Continue with Google Continue with GitHub

No credit card · 7-day full trial

Severity by source

NVD PRIMARY 5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
SUSE MEDIUM
Red Hat 5.5 MEDIUM

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

4
CVSS changed
May 20, 2026 - 18:07 NVD
5.5 (MEDIUM)
Patch released
Apr 18, 2026 - 09:16 nvd
Patch available
Patch available
Apr 16, 2026 - 05:29 EUVD
3d5d488f11776738deab9da336038add95d342d1,1cd6313c8644bfebbd813a05da9daa21b09dd68c,3e79374b03bf9a2f282f0eb1d0ac3776f7e0f28a
CVE Published
Apr 13, 2026 - 13:40 nvd
N/A

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

netfilter: x_tables: restrict xt_check_match/xt_check_target extensions for NFPROTO_ARP

Weiming Shi says:

xt_match and xt_target structs registered with NFPROTO_UNSPEC can be loaded by any protocol family through nft_compat. When such a match/target sets .hooks to restrict which hooks it may run on, the bitmask uses NF_INET_* constants. This is only correct for families whose hook layout matches NF_INET_*: IPv4, IPv6, INET, and bridge all share the same five hooks (PRE_ROUTING ... POST_ROUTING).

ARP only has three hooks (IN=0, OUT=1, FORWARD=2) with different semantics. Because NF_ARP_OUT 1 NF_INET_LOCAL_IN, the .hooks validation silently passes for the wrong reasons, allowing matches to run on ARP chains where the hook assumptions (e.g. state->in being set on input hooks) do not hold. This leads to NULL pointer dereferences; xt_devgroup is one concrete example:

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000044: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000220-0x0000000000000227] RIP: 0010:devgroup_mt+0xff/0x350 Call Trace: <TASK> nft_match_eval (net/netfilter/nft_compat.c:407) nft_do_chain (net/netfilter/nf_tables_core.c:285) nft_do_chain_arp (net/netfilter/nft_chain_filter.c:61) nf_hook_slow (net/netfilter/core.c:623) arp_xmit (net/ipv4/arp.c:666) </TASK> Kernel panic - not syncing: Fatal exception in interrupt

Fix it by restricting arptables to NFPROTO_ARP extensions only. Note that arptables-legacy only supports:

  • arpt_CLASSIFY
  • arpt_mangle
  • arpt_MARK

that provide explicit NFPROTO_ARP match/target declarations.

Threat Intelligence Overview

EPSS Score
0.0%
Top 93% exploitable
Threat Intel
2
1 source
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS CISA Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.0%
Patch available Yes
Active threat Yes
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact· derived
Medium

Priority Score

38
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +28
PoC: 0
Weaponized: 0
Threat intel: +10
Gov advisory: 0

Attack Technique

Null Pointer Dereference MEDIUM

A null pointer dereference occurs when a program attempts to access memory through a pointer that has been set to NULL (address 0x0).

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

More in Canonical

View all
CVE-2011-3544 CRITICAL POC
9.8 Oct 19

Oracle Java SE JDK/JRE 7 and 6 Update 27 and earlier allows remote code execution with complete system compromise throug
CVE-2019-11043 CRITICAL POC
9.8 Oct 28

In PHP versions 7.1.x below 7.1.33, 7.2.x below 7.2.24 and 7.3.x below 7.3.11 in certain configurations of FPM setup it

CVE-2014-6271 CRITICAL POC
9.8 Sep 24

GNU Bash through 4.3 processes trailing strings after function definitions in the values of environment variables, which
CVE-2013-0422 CRITICAL POC
9.8 Jan 10

Multiple vulnerabilities in Oracle Java 7 before Update 11 allow remote attackers to execute arbitrary code by (1) using
CVE-2016-3714 HIGH POC
8.4 May 05

The (1) EPHEMERAL, (2) HTTPS, (3) MVG, (4) MSL, (5) TEXT, (6) SHOW, (7) WIN, and (8) PLT coders in ImageMagick before 6.
CVE-2017-12617 HIGH POC
8.1 Oct 04

When running Apache Tomcat versions 9.0.0.M1 to 9.0.0, 8.5.0 to 8.5.22, 8.0.0.RC1 to 8.0.46 and 7.0.0 to 7.0.81 with HTT
CVE-2016-8735 CRITICAL POC
9.8 Apr 06

Remote code execution is possible with Apache Tomcat before 6.0.48, 7.x before 7.0.73, 8.x before 8.0.39, 8.5.x before 8
CVE-2014-7169 CRITICAL POC
9.8 Sep 25

GNU Bash through 4.3 bash43-025 processes trailing strings after certain malformed function definitions in the values of
CVE-2014-0160 HIGH POC
7.5 Apr 07

The (1) TLS and (2) DTLS implementations in OpenSSL 1.0.1 before 1.0.1g do not properly handle Heartbeat Extension packe
CVE-2016-5195 HIGH POC
7.0 Nov 10

Race condition in mm/gup.c in the Linux kernel 2.x through 4.x before 4.8.3 allows local users to gain privileges by lev
CVE-2013-2423 LOW POC
3.7 Apr 17

Unspecified vulnerability in the Java Runtime Environment (JRE) component in Oracle Java SE 7 Update 17 and earlier, and
CVE-2023-4911 HIGH POC
7.8 Oct 03

Local privilege escalation in the GNU C Library (glibc) dynamic loader ld.so allows unprivileged local users on affected

Same weakness CWE-476 – NULL Pointer Dereference

View all
CVE-2016-0742 HIGH
7.5
CVE-2014-3470 MEDIUM
4.3
CVE-2020-1967 HIGH POC
7.5
CVE-2017-3730 HIGH POC
7.5
CVE-2017-3169 CRITICAL POC
9.8
CVE-2016-4957 HIGH
7.5
CVE-2021-3449 MEDIUM
5.9
CVE-2015-3194 HIGH
7.5

Same technique Denial Of Service

View all
CVE-2015-5119 CRITICAL POC
9.8
CVE-2011-2462 CRITICAL POC
9.8
CVE-2011-0611 HIGH POC
8.8
CVE-2012-1889 HIGH POC
8.8
CVE-2012-0507 CRITICAL POC
9.8
CVE-2014-1761 HIGH POC
7.8
CVE-2015-5122 CRITICAL POC
9.8
CVE-2011-0609 HIGH POC
7.8

Vendor StatusVendor

SUSE

Severity: Medium
Product Status
SUSE Linux Enterprise Server 12 SP5-LTSS Affected
SUSE Linux Enterprise Server 12 SP5-LTSS Affected
SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 Affected
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise Desktop 15 SP7 Fixed

Threat IntelligenceMISP

CISA Advisories
ICSA-26-209-04 ICSA-26-295-11
Sources: CISA (public domain)

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-31424 ADVISORY https://ubuntu.com/security/notices/USN-8567-1 ADVISORY https://vuldb.com/vuln/357156 REF https://cert-portal.siemens.com/productcert/html/ssa-019113.html REF https://cert-portal.siemens.com/productcert/html/ssa-082556.html REF https://cert-portal.siemens.com/productcert/html/ssa-457936.html REF https://git.kernel.org/stable/c/1cd6313c8644bfebbd813a05da9daa21b09dd68c REF https://git.kernel.org/stable/c/3d5d488f11776738deab9da336038add95d342d1 REF https://git.kernel.org/stable/c/3e79374b03bf9a2f282f0eb1d0ac3776f7e0f28a REF https://git.kernel.org/stable/c/80e3c75f71c3ea1e62fcb032382de13e00a68f8b REF https://git.kernel.org/stable/c/d9a0af9e43416aa50c0595e15fa01365a1c72c49 REF https://git.kernel.org/stable/c/dc3e27dd7d76e21106b8f9bbdc31f5da74a89014 REF https://git.kernel.org/stable/c/e7e1b6bcb389c8708003d40613a59ff2496f6b1f REF https://git.kernel.org/stable/c/f00ac65c90ea475719e08d629e2e26c8b4e6999b

Search Externally

GitHub PoC Exploit-DB PacketStorm Snyk Rapid7 Nuclei Templates Trickest PoC
Back

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy