8.2
HIGH
CVSS 3.1
CVE-2026-23456
netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case
Overview
Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case In decode_int(), the CONS case calls get_bits(bs, 2) to read a length value, then calls get_uint(bs, len) without checking that len bytes remain in the buffer. The existing boundary check only validates the 2 bits for get_bits(), not the subsequent 1-4 bytes that get_uint() reads. This allows a malformed H.323/RAS packet to cause a 1-4 byte slab-out-of-bounds read. Add a boundary check for len bytes after get_bits() and before get_uint().
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 | HIGH | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
Fix an out-of-bounds read vulnerability in netfilter's H.323 connection tracking module.
- Apply the patch for netfilter: nf_conntrack_h323.
- Add a boundary check for get_uint() arguments.
- Ensure buffer boundaries are validated before reading data.
Public PoC/Exploit Available at Github
CVE-2026-23456 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
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-2026-23456.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-23456 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-2026-23456
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).
None
PowerShell
Updated: 2 months ago
0 stars
0 fork
0 watcher
Born at : June 9, 2026, 1:55 a.m.
This repo has been linked 2 different CVEs too.
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-23456 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-23456 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: corrección de lectura fuera de límites (OOB) en el caso CONS de decode_int() En decode_int(), el caso CONS llama a get_bits(bs, 2) para leer un valor de longitud, luego llama a get_uint(bs, len) sin comprobar que len bytes permanezcan en el búfer. La comprobación de límites existente solo valida los 2 bits para get_bits(), no los 1-4 bytes subsiguientes que lee get_uint(). Esto permite que un paquete H.323/RAS malformado cause una lectura fuera de límites de slab de 1-4 bytes. Añadir una comprobación de límites para len bytes después de get_bits() y antes de get_uint(). -
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': 'a2cd54b9348e485d338b3c132338a4410c99afaf', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': 'c95dc674ebf01ecfb40388b6facfc89b81fed3b7', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': '41b417ff73a24b2c68134992cc44c88db27f482d', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': '52235bf88159a1ef16434ab49e47e99c8a09ab20', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': '774a434f8c9c8602a976b2536f65d0172a07f4d2', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': '6bce72daeccca9aa1746e92d6c3d4784e71f2ebb', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': 'fb6c3596823ec5dd09c2123340330d7448f51a59', 'versionType': 'git'}, {'status': 'affected', 'version': '5e35941d990123f155b02d5663e51a24f816b6f3', 'lessThan': '1e3a3593162c96e8a8de48b1e14f60c3b57fca8a', '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/1e3a3593162c96e8a8de48b1e14f60c3b57fca8a Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/41b417ff73a24b2c68134992cc44c88db27f482d Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/52235bf88159a1ef16434ab49e47e99c8a09ab20 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/6bce72daeccca9aa1746e92d6c3d4784e71f2ebb Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/774a434f8c9c8602a976b2536f65d0172a07f4d2 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/a2cd54b9348e485d338b3c132338a4410c99afaf Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/c95dc674ebf01ecfb40388b6facfc89b81fed3b7 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/fb6c3596823ec5dd09c2123340330d7448f51a59 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:L/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/a2cd54b9348e485d338b3c132338a4410c99afaf Added Reference https://git.kernel.org/stable/c/c95dc674ebf01ecfb40388b6facfc89b81fed3b7 -
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: fix OOB read in decode_int() CONS case In decode_int(), the CONS case calls get_bits(bs, 2) to read a length value, then calls get_uint(bs, len) without checking that len bytes remain in the buffer. The existing boundary check only validates the 2 bits for get_bits(), not the subsequent 1-4 bytes that get_uint() reads. This allows a malformed H.323/RAS packet to cause a 1-4 byte slab-out-of-bounds read. Add a boundary check for len bytes after get_bits() and before get_uint(). Added Reference https://git.kernel.org/stable/c/1e3a3593162c96e8a8de48b1e14f60c3b57fca8a Added Reference https://git.kernel.org/stable/c/41b417ff73a24b2c68134992cc44c88db27f482d Added Reference https://git.kernel.org/stable/c/52235bf88159a1ef16434ab49e47e99c8a09ab20 Added Reference https://git.kernel.org/stable/c/6bce72daeccca9aa1746e92d6c3d4784e71f2ebb Added Reference https://git.kernel.org/stable/c/774a434f8c9c8602a976b2536f65d0172a07f4d2 Added Reference https://git.kernel.org/stable/c/fb6c3596823ec5dd09c2123340330d7448f51a59
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.