CVE-2026-23455 — CVE & Security Advisory Radar

🎯 CVE-2026-23455 CRITICAL 9.1 🔥 EPSS 1.3% 🇪🇺 EUVD

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CVE-2026-23455 | In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of

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

netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()

In DecodeQ931(), the UserUserIE code path reads a 16-bit length from
the packet, then decrements it by 1 to skip the protocol discriminator
byte before passing it to DecodeH323_UserInformation(). If the encoded
length is 0, the decrement wraps to -1, which is then passed as a
large value to the decoder, leading to an out-of-bounds read.

Add a check to ensure len is positive after the decrement.

Klassifikation & Betroffenheit:

Linux Linux patch: 6.1.167Linux patch: 5.10.253Linux patch: 6.18.20Linux patch: 5.15.203Linux 5e35941d990123f155b02d5663e51a24f816b6f3 <9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8Linux patch: 6.19.10Linux 5e35941d990123f155b02d5663e51a24f816b6f3 <f5e4f4e4cdb75ec36802059a94195a31f193da60Linux patch: 6.6.130

Improper Control of Generation of Code ('Code Injection') 🎯 Medium

The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

🛡️ Empfohlene Mitigation: Refactor your program so that you do not have to dynamically generate code.

Vollständige Definition bei MITRE ➔

⚔️ Typische Angriffsmuster (CAPEC):

CAPEC-35 · Leverage Executable Code in Non-Executab… (Very High) CAPEC-77 · Manipulating User-Controlled Variables (Very High) CAPEC-242 · Code Injection (High)

🎯 ATT&CK-Techniken (Kill-Chain-Verhalten):

T1027.006 · Obfuscated Files or Information: H… T1027.009 · Obfuscated Files or Information: E… T1564.009 · Hide Artifacts: Resource Forking

🧩 Ähnliche Schwachstellen (Hersteller/Klasse/Score-Band):

CVE-2026-74475 10.0 CVE-2026-74309 10.0 CVE-2026-74280 10.0 CVE-2026-74279 10.0 CVE-2026-72421 10.0

🩹 Patch verfügbar (OSV):

🩹 Kernel ≥ 5.10.253 🩹 Kernel ≥ 5.15.203 🩹 Kernel ≥ 6.1.167 🩹 Kernel ≥ 6.6.130 🩹 Kernel ≥ 6.12.78 🩹 Kernel ≥ 6.18.20

📚 Referenzen & Quellen:

🇪🇺 Original-Eintrag (ENISA EUVD) 🇺🇸 NVD-Eintrag

Ausnutzungs-Zeitleiste:

Reserviert 2026

Veröffentlicht 04/2026

Heute 16.09.

CVSS-Vektor-Analyse: 9.1

AV · Angriffsvektor Netzwerk

AC · Komplexität Gering

PR · Privilegien Keine

UI · Interaktion Keine

S · Scope Unverändert

C · Vertraulichkeit Hoch

I · Integrität Keine

A · Verfügbarkeit Hoch

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

Veröffentlicht:03.04.2026

Aktualisiert:24.07.2026 22:10

Assigner (CNA):Linux

EUVD-ID:EUVD-2026-18711

Quellen: 🇪🇺 EUVD-Datenbank (ENISA) + 🇺🇸 NVD-Anreicherung · 24-h-Cache

CWE-94: Code Injection ✓ Offizieller Patch / Advisory verfügbar

💡 Gegenmaßnahme: Kernel-Paket aktualisieren (apt upgrade linux-image / yum update kernel) und System neu starten.

Tier	2026-08-29	2026-09-16
≥90 %	4	0
≥50 %	4	0
≥10 %	3	0
<10 %	304	300

9.1 CRITICAL

🇪🇺 EUVD

EPSS

1.3%

CVE-2026-23455 🌐 Netzwerk (Remote) 🔓 Keine Authentifizierung nötig

Linux

CVE-2026-23455 | In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of

CWE-94: Code Injection ✓ Offizieller Patch / Advisory verfügbar

💡 Gegenmaßnahme: Kernel-Paket aktualisieren (apt upgrade linux-image / yum update kernel) und System neu starten.

03.04.2026

🛡️ Details ➔

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