CVE-2026-23398

mediumpriority · track · 32EPSS 0.001 · 3 %ileexploit · PoCDEEUFRRUUS

grimoire priorityP1 · Urgent

Exploitable?

Public exploit

2 exploits · PoC

Likely / severe?

0.13% (3rd) EPSS

CVSS 5.5 · medium

Is it mine?

105 products

Check your exposure

Who says so?

7 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

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.

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

No vendor fix yet; a mitigation is available.

MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)siemens_psirt
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)siemens_psirt
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)siemens_psirt
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)siemens_psirt
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
MitigationSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)siemens_psirt
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
MitigationSIMATIC S7-1500 TM MFP - GNU/Linux subsystemsiemens_psirt
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)cisa_csaf_ot
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)cisa_csaf_ot
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)cisa_csaf_ot
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)cisa_csaf_ot
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
MitigationSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)cisa_csaf_ot
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
MitigationSIMATIC S7-1500 TM MFP - GNU/Linux subsystemcisa_csaf_ot
Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.
No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)siemens_psirt
Currently no fix is available
No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)siemens_psirt
Currently no fix is available
No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)siemens_psirt
Currently no fix is available
No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)siemens_psirt
Currently no fix is available
No fix availableSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)siemens_psirt
Currently no fix is available
No fix availableSIMATIC S7-1500 TM MFP - GNU/Linux subsystemsiemens_psirt
Currently no fix is available
No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)cisa_csaf_ot
Currently no fix is available
No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)cisa_csaf_ot
Currently no fix is available
No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)cisa_csaf_ot
Currently no fix is available
No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)cisa_csaf_ot
Currently no fix is available
No fix availableSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)cisa_csaf_ot
Currently no fix is available
No fix availableSIMATIC S7-1500 TM MFP - GNU/Linux subsystemcisa_csaf_ot
Currently no fix is available

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5.2–7.5

v3.15.5mediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 1.8 · impact 3.6

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · CISA US

v3.17.5highAV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · Siemens ProductCERT DE

v3.15.2mediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:Psecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-476USprimaryCWE-476USCWE-476USCWE-476US

exploits (2)

Public proof-of-concept and weaponised exploit code.

JohannesLks/CVE-2026-23398icmp_tag_validation() NULL derefPoC · poc_in_github
zpol/cve-2026-23398-pocFunctional LAB with CVE-2026-23398 PoC PoC · poc_in_github

affected products (105)

Products and version ranges known to be affected.

Debian Linuxall versionscert_bundDEcpe:/o:debian:debian_linux:-
Dell Avamarall versionscert_bundDEcpe:/a:dell:avamar:-
Dell NetWorkerall versionscert_bundDEcpe:/a:dell:networker:-
Google Container-Optimized OSall versionscert_bundDEcpe:/o:google:container-optimized_os:-
Open Source Linux Kernelall versionscert_bundDEcpe:/o:linux:linux_kernel:-
Oracle Linuxall versionscert_bundDEcpe:/o:oracle:linux:-
SUSE Linuxall versionscert_bundDEcpe:/o:suse:suse_linux:-
SUSE openSUSEall versionscert_bundDEcpe:/o:suse:opensuse:-
Siemens SIMATIC S7 1500 CPUall versionscert_bundDEcpe:/h:siemens:simatic_s7:1500_cpu
Ubuntu Linuxall versionscert_bundDEcpe:/o:canonical:ubuntu_linux:-
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)≤ vers:intdot/>=3.1.7cisa_csaf_otUS
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)≤ vers:intdot/>=3.1.7cisa_csaf_otUS
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)≤ vers:intdot/>=3.1.7cisa_csaf_otUS
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)≤ vers:intdot/>=3.1.7cisa_csaf_otUS
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem≤ vers:all/*cisa_csaf_otUS
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)≤ vers:intdot/>=3.1.7cisa_csaf_otUS
Linux Linux≤ 3.14enisa_euvdEU
Linux Linuxall versionsenisa_euvdEU
Linux Linux< 5.10.253enisa_euvdEU
Linux Linux< 5.15.203enisa_euvdEU

showing 20 of 105

advisories (9)

Vendor and ecosystem advisories describing this.

SSA-019113SSA-019113: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.62026-07-14csaf · siemens_psirtDE
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.6 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens is preparing further fix versions and recommends specific countermeasures for products where fixes are not, or not yet available. SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.6 is no longer maintained and there won't be any update to the CVE list anymore. Please update to the latest version. Note: This SSA advises vulnerabilities for firmware version V3.1.6 only; for version V3.1.7 refer to SSA-457936.
SSA-082556SSA-082556: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.52025-06-10csaf · siemens_psirtDE
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.5 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens is preparing further fixes and recommends specific mitigations for products where fixes are not or not yet available. SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.5 is no longer maintained and there won't be any update to the CVE list anymore. Please update to the latest version. Note: This SSA advises vulnerabilities for firmware version V3.1.5 only; for version V3.1.6 refer to SSA-019113.
SSA-457936SSA-457936: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.72026-10-13csaf · siemens_psirtDE
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.7 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fixes and recommends specific mitigations for products where fixes are not or not yet available.
SSA-784472SSA-784472: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1.12026-10-13csaf · siemens_psirtDE
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1.1. Siemens is preparing fixes and recommends specific mitigations for products where fixes are not or not yet available.
WID-SEC-W-2026-0879Linux Kernel: Mehrere SchwachstellenDeutsch2026-03-25csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um einen Denial of Service Zustand herbeizuführen oder einen nicht näher spezifizierten Angriff durchzuführen.
ICSA-26-209-04Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP2026-07-14icsa · cisa_csaf_otUS
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.6 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fix versions and recommends specific countermeasures for products where fixes are not, or not yet available.
ICSA-26-295-11Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP2026-10-13icsa · cisa_csaf_otUS
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.7 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fixes and recommends specific mitigations for products where fixes are not or not yet available.
ICSA-26-295-16Siemens SIMATIC S7-1500 TM MFP2026-10-13icsa · cisa_csaf_otUS
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1.1. Siemens is preparing fixes and recommends specific mitigations for products where fixes are not or not yet available.
CERTFR-2026-AVI-1298Multiples vulnérabilités dans les produits SiemensFrançais2026-10-13vendor · certfrFR

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund cisa_csaf_ot siemens_psirt certfr NVD CVE.org MITRE

published 2026-03-26modified 2026-07-14

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references (27)

External citations — patches, advisories, analysis.

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