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CVE-2026-23398· NVD / CVE Program· CNA Linux

icmp: fix NULL pointer dereference in icmp_tag_validation()

In the Linux kernel, the following vulnerability has been resolved: icmp: fix NULL pointer dereference in icmp_tag_validation() icmp_tag_validation() unconditionally dereferences the result of rcu_dereference(inet_protos[proto]) without checking for NULL. The inet_protos[] array is sparse -- only about 15 of 256 protocol numbers have registered handlers. When ip_no_pmtu_disc is set to 3 (hardened PMTU mode) and the kernel receives an ICMP Fragmentation Needed error with a quoted inner IP header containing an unregistered protocol number, the NULL dereference causes a kernel panic in softirq context. Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:icmp_unreach (net/ipv4/icmp.c:1085 net/ipv4/icmp.c:1143) Call Trace: <IRQ> icmp_rcv (net/ipv4/icmp.c:1527) ip_protocol_deliver_rcu (net/ipv4/ip_input.c:207) ip_local_deliver_finish (net/ipv4/ip_input.c:242) ip_local_deliver (net/ipv4/ip_input.c:262) ip_rcv (net/ipv4/ip_input.c:573) __netif_receive_skb_one_core (net/core/dev.c:6164) process_backlog (net/core/dev.c:6628) handle_softirqs (kernel/softirq.c:561) </IRQ> Add a NULL check before accessing icmp_strict_tag_validation. If the protocol has no registered handler, return false since it cannot perform strict tag validation.

MediumCVSS 5.5 · v3.1—Proof of concept Fix available
Published
Mar 26, 2026
Updated
Sep 8, 2026
EPSS
0.1% · 2th percentile
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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%

Affected systems

VendorProduct
linuxlinux kernel

Affected versions

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

  • linux linux kernel3.14.1 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 6.12.78
  • linux linux kernel6.13 and later · before 6.18.20
  • linux linux kernel6.19 and later · before 6.19.10
  • linux linux kernel3.14
  • linux linux kernel7.0

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

    • 3.14affected
    • 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e and later · before 571d9d7b650f02d1e38c01128817868bceac9eddaffected · git
    • 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e and later · before d783fa413c702ff0f8f8bea63f862e28eeaf39e3affected · git
    • 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e and later · before 1f9f2c6d4b2a613b7756fc5679c5116ba2ca0161affected · git
    • 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e and later · before b61529c357f1ee4d64836eb142a542d2e7ad67ceaffected · git
    • 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e and later · before 9647e99d2a617c355d2b378be0ff6d0e848fd579affected · git
    • 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e and later · before d938dd5a0ad780c891ea3bc94cae7405f11e618aaffected · git
    • 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e and later · before 1e4e2f5e48cec0cccaea9815fb9486c084ba41e2affected · git
    • 8ed1dc44d3e9e8387a104b1ae8f92e9a3fbf1b1e and later · before 614aefe56af8e13331e50220c936fc0689cf5675affected · git
    • before 3.14not affected · semver

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 6.19.10-16.19.10-1
SUSE:Linux Enterprise Micro 5.2kernel-defaultbefore 5.3.18-150300.59.241.15.3.18-150300.59.241.1
SUSE:Linux Enterprise Micro 5.2kernel-default-basebefore 5.3.18-150300.59.241.1.150300.18.144.15.3.18-150300.59.241.1.150300.18.144.1
SUSE:Linux Enterprise Micro 5.2kernel-rtbefore 5.3.18-150300.241.15.3.18-150300.241.1
SUSE:Linux Enterprise Micro 5.2kernel-sourcebefore 5.3.18-150300.59.241.15.3.18-150300.59.241.1
SUSE:Linux Enterprise Micro 5.2kernel-source-rtbefore 5.3.18-150300.241.15.3.18-150300.241.1

Same product

linux: all records

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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 Linux1e4e2f5e48cec0cccaea9815fb9486c084ba41e2Vendor (CNA)
Linux Linux1f9f2c6d4b2a613b7756fc5679c5116ba2ca0161Vendor (CNA)
Linux Linux571d9d7b650f02d1e38c01128817868bceac9eddVendor (CNA)
Linux Linux614aefe56af8e13331e50220c936fc0689cf5675Vendor (CNA)
Linux Linux9647e99d2a617c355d2b378be0ff6d0e848fd579Vendor (CNA)
Linux Linuxb61529c357f1ee4d64836eb142a542d2e7ad67ceVendor (CNA)
Linux Linuxd783fa413c702ff0f8f8bea63f862e28eeaf39e3Vendor (CNA)
Linux Linuxd938dd5a0ad780c891ea3bc94cae7405f11e618aVendor (CNA)
debian:linux6.1.170-1 · Debian:12Package registry (OSV)
suse:kernel-default5.3.18-150300.59.241.1 · SUSE:Linux Enterprise Micro 5.2Package registry (OSV)
suse:kernel-default-base5.3.18-150300.59.241.1.150300.18.144.1 · SUSE:Linux Enterprise Micro 5.2Package registry (OSV)
suse:kernel-rt5.3.18-150300.241.1 · SUSE:Linux Enterprise Micro 5.2Package registry (OSV)
suse:kernel-source5.3.18-150300.59.241.1 · SUSE:Linux Enterprise Micro 5.2Package registry (OSV)
suse:kernel-source-rt5.3.18-150300.241.1 · SUSE:Linux Enterprise Micro 5.2Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×2

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:12026-04-05
Proof-of-concept repository on GitHubstars:12026-04-08

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.

  1. Published
  2. First PoC+10 d
  3. TodaySep 30, 2026+188 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

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.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

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

All records