9.1
CRITICAL
CVSS 3.1
CVE-2026-23455
netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()
Overview
Description
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.
Details
INFO
Published Date :
April 3, 2026, 4:16 p.m.
Last Modified :
July 24, 2026, 10:10 p.m.
Remotely Exploit :
Yes !
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework
for assessing the severity of vulnerabilities in software and systems.
We collect and displays CVSS scores from various sources for each CVE.
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
Apply the Linux kernel patch for netfilter to fix an out-of-bounds read vulnerability.
- Patch the Linux kernel netfilter component.
- Ensure length is positive after decrement.
- Update to the corrected kernel version.
References
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-23455.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-23455 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-23455
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-23455 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-23455 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Jul. 24, 2026
Action Type Old Value New Value Added Translation Title: Linux, Description: En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta: netfilter: nf_conntrack_h323: comprobación de longitud cero en DecodeQ931() En DecodeQ931(), la ruta de código UserUserIE lee una longitud de 16 bits del paquete, luego la decrementa en 1 para omitir el byte discriminador del protocolo antes de pasarla a DecodeH323_UserInformation(). Si la longitud codificada es 0, el decremento se ajusta a -1, que luego se pasa como un valor grande al decodificador, lo que lleva a una lectura fuera de límites. Se añade una comprobación para asegurar que 'len' sea positivo después del decremento. -
CVE Modified by 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
Jul. 14, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.6', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.5', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.6', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.5', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.6', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.5', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.6', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.5', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIPLUS S7-1500 CPU 1518-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.6', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'Siemens', 'product': 'SIPLUS S7-1500 CPU 1518-4 PN/DP MFP', 'versions': [{'status': 'affected', 'version': 'V3.1.5', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}] Added Reference https://cert-portal.siemens.com/productcert/html/ssa-019113.html Added Reference https://cert-portal.siemens.com/productcert/html/ssa-082556.html -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': '2121f5fbe88daff0f1fc5bc47d359426c74b86b0', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': '65fa92f79677858b14b9e4b7275f26639afe2710', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': '495e97af9e7249ee02b72bb1d0848a6efc3700f4', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': 'f5e4f4e4cdb75ec36802059a94195a31f193da60', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': '633e8f87dad32263f6a57dccdb873f042c062111', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': '9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': 'b652b05d51003ac074b912684f9ec7486231717b', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': 'f173d0f4c0f689173f8cdac79991043a4a89bf66', 'versionType': 'git'}], 'programFiles': ['net/netfilter/nf_conntrack_h323_asn1.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '2.6.17'}, {'status': 'unaffected', 'version': '0', 'lessThan': '2.6.17', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.10.253', 'versionType': 'semver', 'lessThanOrEqual': '5.10.*'}, {'status': 'unaffected', 'version': '5.15.203', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.167', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.130', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.78', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.20', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '6.19.10', 'versionType': 'semver', 'lessThanOrEqual': '6.19.*'}, {'status': 'unaffected', 'version': '7.0', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/netfilter/nf_conntrack_h323_asn1.c'], 'defaultStatus': 'affected'}] -
Initial Analysis by [email protected]
May. 26, 2026
Action Type Old Value New Value Added CWE CWE-125 Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.2 up to (excluding) 6.6.130 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.11 up to (excluding) 5.15.203 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.16 up to (excluding) 6.1.167 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.12.78 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.18.20 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.19 up to (excluding) 6.19.10 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 2.6.17 up to (excluding) 5.10.253 Added Reference Type kernel.org: https://git.kernel.org/stable/c/2121f5fbe88daff0f1fc5bc47d359426c74b86b0 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/495e97af9e7249ee02b72bb1d0848a6efc3700f4 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/633e8f87dad32263f6a57dccdb873f042c062111 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/65fa92f79677858b14b9e4b7275f26639afe2710 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/b652b05d51003ac074b912684f9ec7486231717b Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/f173d0f4c0f689173f8cdac79991043a4a89bf66 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/f5e4f4e4cdb75ec36802059a94195a31f193da60 Types: Patch -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Apr. 27, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Apr. 18, 2026
Action Type Old Value New Value Added Reference https://git.kernel.org/stable/c/2121f5fbe88daff0f1fc5bc47d359426c74b86b0 Added Reference https://git.kernel.org/stable/c/65fa92f79677858b14b9e4b7275f26639afe2710 -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Apr. 03, 2026
Action Type Old Value New Value Added Description 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. Added Reference https://git.kernel.org/stable/c/495e97af9e7249ee02b72bb1d0848a6efc3700f4 Added Reference https://git.kernel.org/stable/c/633e8f87dad32263f6a57dccdb873f042c062111 Added Reference https://git.kernel.org/stable/c/9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8 Added Reference https://git.kernel.org/stable/c/b652b05d51003ac074b912684f9ec7486231717b Added Reference https://git.kernel.org/stable/c/f173d0f4c0f689173f8cdac79991043a4a89bf66 Added Reference https://git.kernel.org/stable/c/f5e4f4e4cdb75ec36802059a94195a31f193da60
EPSS is a daily estimate of the probability of exploitation activity
being observed over the next 30 days. Following chart shows the EPSS
score history of the vulnerability.