Answer in brief
CVE-2026-23457 records a High severity (CVSS 8.6) vulnerability in netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2026-23457 records a High severity (CVSS 8.6) vulnerability in netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.6. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <ed81b6a7012485acdb9c6c80735a0b7d8e5e1873 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <b75209debb9adab287b3caa982f77788c1e15027 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <528b4509c9dfc272e2e92d811915e5211650d383 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <75fcaee5170e7dbbee778927134ef2e9568b4659 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <865dba58958c3a86786f89a501971ab0e3ec6ba9 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <d4f17256544cc37f6534a14a27a9dec3540c2015 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <fbce58e719a17aa215c724473fd5baaa4a8dc57c | ed81b6a7012485acdb9c6c80735a0b7d8e5e1873, cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f, b75209debb9adab287b3caa982f77788c1e15027, 528b4509c9dfc272e2e92d811915e5211650d383, 75fcaee5170e7dbbee778927134ef2e9568b4659, 865dba58958c3a86786f89a501971ab0e3ec6ba9, d4f17256544cc37f6534a14a27a9dec3540c2015, fbce58e719a17aa215c724473fd5baaa4a8dc57c |
| Linux/Linuxgeneric | 2.6.34 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
Published upstream
Apr 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 14, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 14, 2026
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.
Quoted source text, attributed separately from HOL analysis.
CVSS is 8.6. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <ed81b6a7012485acdb9c6c80735a0b7d8e5e1873 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <b75209debb9adab287b3caa982f77788c1e15027 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <528b4509c9dfc272e2e92d811915e5211650d383 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <75fcaee5170e7dbbee778927134ef2e9568b4659 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <865dba58958c3a86786f89a501971ab0e3ec6ba9 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <d4f17256544cc37f6534a14a27a9dec3540c2015 || >=f5b321bd37fbec9188feb1f721ab46a5ac0b35da <fbce58e719a17aa215c724473fd5baaa4a8dc57c | ed81b6a7012485acdb9c6c80735a0b7d8e5e1873, cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f, b75209debb9adab287b3caa982f77788c1e15027, 528b4509c9dfc272e2e92d811915e5211650d383, 75fcaee5170e7dbbee778927134ef2e9568b4659, 865dba58958c3a86786f89a501971ab0e3ec6ba9, d4f17256544cc37f6534a14a27a9dec3540c2015, fbce58e719a17aa215c724473fd5baaa4a8dc57c |
| Linux/Linuxgeneric | 2.6.34 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
Published upstream
Apr 3, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Jul 14, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 14, 2026
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.
Quoted source text, attributed separately from HOL analysis.