Linux Kernel up to 7.0-rc4 SDP Parser sip_help_tcp Content-Length data authenticity

CVSS Meta Temp Score
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CTI Interest Score
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6.9$0-$5k0.00

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel up to 7.0-rc4. Affected by this issue is the function sip_help_tcp of the component SDP Parser. Such manipulation of the argument Content-Length leads to data authenticity. This vulnerability is documented as CVE-2026-23457. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.0-rc4 and classified as critical. Affected by this issue is the function sip_help_tcp of the component SDP Parser. The manipulation of the argument Content-Length with an unknown input leads to a data authenticity vulnerability. Using CWE to declare the problem leads to CWE-345. The product does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data. The impact remains unknown. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp() sip_help_tcp() parses the SIP Content-Length header with simple_strtoul(), which returns unsigned long, but stores the result in unsigned int clen. On 64-bit systems, values exceeding UINT_MAX are silently truncated before computing the SIP message boundary. For example, Content-Length 4294967328 (2^32 + 32) is truncated to 32, causing the parser to miscalculate where the current message ends. The loop then treats trailing data in the TCP segment as a second SIP message and processes it through the SDP parser. Fix this by changing clen to unsigned long to match the return type of simple_strtoul(), and reject Content-Length values that exceed the remaining TCP payload length.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-23457 since 01/13/2026. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 05/27/2026).

The vulnerability scanner Nessus provides a plugin with the ID 304982 (Linux Distros Unpatched Vulnerability : CVE-2026-23457), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10 or 7.0-rc5 eliminates this vulnerability. Applying the patch b75209debb9adab287b3caa982f77788c1e15027/528b4509c9dfc272e2e92d811915e5211650d383/75fcaee5170e7dbbee778927134ef2e9568b4659/865dba58958c3a86786f89a501971ab0e3ec6ba9/d4f17256544cc37f6534a14a27a9dec3540c2015/fbce58e719a17aa215c724473fd5baaa4a8dc57c is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (304982) and EUVD (EUVD-2026-18714). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.0
VulDB Meta Temp Score: 6.9

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 8.6
CNA Vector (Linux): 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Data authenticity
CWE: CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 304982
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-23457

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.167/6.6.130/6.12.78/6.18.20/6.19.10/7.0-rc5
Patch: b75209debb9adab287b3caa982f77788c1e15027/528b4509c9dfc272e2e92d811915e5211650d383/75fcaee5170e7dbbee778927134ef2e9568b4659/865dba58958c3a86786f89a501971ab0e3ec6ba9/d4f17256544cc37f6534a14a27a9dec3540c2015/fbce58e719a17aa215c724473fd5baaa4a8dc57c

Timelineinfo

01/13/2026 CVE reserved
04/03/2026 +79 days Advisory disclosed
04/03/2026 +0 days VulDB entry created
05/27/2026 +54 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-23457 (🔒)
GCVE (CVE): GCVE-0-2026-23457
GCVE (VulDB): GCVE-100-355136
EUVD: 🔒

Entryinfo

Created: 04/03/2026 18:10
Updated: 05/27/2026 03:52
Changes: 04/03/2026 18:10 (60), 04/08/2026 00:18 (2), 04/19/2026 20:18 (1), 05/27/2026 03:52 (11)
Complete: 🔍
Cache ID: 216::103

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