Answer in brief
CVE-2026-23456 records a High severity (CVSS 8.2) vulnerability in netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case. 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-2026-23456 records a High severity (CVSS 8.2) vulnerability in netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case. 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 8.2. 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 | >=5e35941d990123f155b02d5663e51a24f816b6f3 <a2cd54b9348e485d338b3c132338a4410c99afaf || >=5e35941d990123f155b02d5663e51a24f816b6f3 <c95dc674ebf01ecfb40388b6facfc89b81fed3b7 || >=5e35941d990123f155b02d5663e51a24f816b6f3 <41b417ff73a24b2c68134992cc44c88db27f482d || >=5e35941d990123f155b02d5663e51a24f816b6f3 <52235bf88159a1ef16434ab49e47e99c8a09ab20 || >=5e35941d990123f155b02d5663e51a24f816b6f3 <774a434f8c9c8602a976b2536f65d0172a07f4d2 || >=5e35941d990123f155b02d5663e51a24f816b6f3 <6bce72daeccca9aa1746e92d6c3d4784e71f2ebb || >=5e35941d990123f155b02d5663e51a24f816b6f3 <fb6c3596823ec5dd09c2123340330d7448f51a59 || >=5e35941d990123f155b02d5663e51a24f816b6f3 <1e3a3593162c96e8a8de48b1e14f60c3b57fca8a | a2cd54b9348e485d338b3c132338a4410c99afaf, c95dc674ebf01ecfb40388b6facfc89b81fed3b7, 41b417ff73a24b2c68134992cc44c88db27f482d, 52235bf88159a1ef16434ab49e47e99c8a09ab20, 774a434f8c9c8602a976b2536f65d0172a07f4d2, 6bce72daeccca9aa1746e92d6c3d4784e71f2ebb, fb6c3596823ec5dd09c2123340330d7448f51a59, 1e3a3593162c96e8a8de48b1e14f60c3b57fca8a |
| Linux/Linuxgeneric | 2.6.17 | 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_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().
Quoted source text, attributed separately from HOL analysis.
CVSS is 8.2. 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 | >=5e35941d990123f155b02d5663e51a24f816b6f3 <a2cd54b9348e485d338b3c132338a4410c99afaf || >=5e35941d990123f155b02d5663e51a24f816b6f3 <c95dc674ebf01ecfb40388b6facfc89b81fed3b7 || >=5e35941d990123f155b02d5663e51a24f816b6f3 <41b417ff73a24b2c68134992cc44c88db27f482d || >=5e35941d990123f155b02d5663e51a24f816b6f3 <52235bf88159a1ef16434ab49e47e99c8a09ab20 || >=5e35941d990123f155b02d5663e51a24f816b6f3 <774a434f8c9c8602a976b2536f65d0172a07f4d2 || >=5e35941d990123f155b02d5663e51a24f816b6f3 <6bce72daeccca9aa1746e92d6c3d4784e71f2ebb || >=5e35941d990123f155b02d5663e51a24f816b6f3 <fb6c3596823ec5dd09c2123340330d7448f51a59 || >=5e35941d990123f155b02d5663e51a24f816b6f3 <1e3a3593162c96e8a8de48b1e14f60c3b57fca8a | a2cd54b9348e485d338b3c132338a4410c99afaf, c95dc674ebf01ecfb40388b6facfc89b81fed3b7, 41b417ff73a24b2c68134992cc44c88db27f482d, 52235bf88159a1ef16434ab49e47e99c8a09ab20, 774a434f8c9c8602a976b2536f65d0172a07f4d2, 6bce72daeccca9aa1746e92d6c3d4784e71f2ebb, fb6c3596823ec5dd09c2123340330d7448f51a59, 1e3a3593162c96e8a8de48b1e14f60c3b57fca8a |
| Linux/Linuxgeneric | 2.6.17 | 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_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().
Quoted source text, attributed separately from HOL analysis.