Answer in brief
CVE-2026-31664 records a Medium severity (CVSS 5.5) vulnerability in xfrm: clear trailing padding in build_polexpire(). 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-2026-31664 records a Medium severity (CVSS 5.5) vulnerability in xfrm: clear trailing padding in build_polexpire(). 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 5.5. 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 | >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a5127501c8d30b5728791b1e340284ca5c9cc4bd || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e6f4ffe8596947a595c9544e73a73adcb0568b88 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ac6985903db047eaff54db929e4bf6b06782788e || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c221ed63a2769a0af8bd849dfe25740048f34ef4 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <eda30846ea54f8ed218468e5480c8305ca645e37 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b1dfd6b27df35ef4f87825aa5f607378d23ff0f2 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e1af65c669ebb1666c54576614c01a7f9ffcfff6 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <71a98248c63c535eaa4d4c22f099b68d902006d0 | a5127501c8d30b5728791b1e340284ca5c9cc4bd, e6f4ffe8596947a595c9544e73a73adcb0568b88, ac6985903db047eaff54db929e4bf6b06782788e, c221ed63a2769a0af8bd849dfe25740048f34ef4, eda30846ea54f8ed218468e5480c8305ca645e37, b1dfd6b27df35ef4f87825aa5f607378d23ff0f2, e1af65c669ebb1666c54576614c01a7f9ffcfff6, 71a98248c63c535eaa4d4c22f099b68d902006d0 |
| Linux/Linuxgeneric | 2.6.12 | 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 24, 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: xfrm: clear trailing padding in build_polexpire() build_expire() clears the trailing padding bytes of struct xfrm_user_expire after setting the hard field via memset_after(), but the analogous function build_polexpire() does not do this for struct xfrm_user_polexpire. The padding bytes after the __u8 hard field are left uninitialized from the heap allocation, and are then sent to userspace via netlink multicast to XFRMNLGRP_EXPIRE listeners, leaking kernel heap memory contents. Add the missing memset_after() call, matching build_expire().
Quoted source text, attributed separately from HOL analysis.
CVSS is 5.5. 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 | >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a5127501c8d30b5728791b1e340284ca5c9cc4bd || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e6f4ffe8596947a595c9544e73a73adcb0568b88 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ac6985903db047eaff54db929e4bf6b06782788e || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c221ed63a2769a0af8bd849dfe25740048f34ef4 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <eda30846ea54f8ed218468e5480c8305ca645e37 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b1dfd6b27df35ef4f87825aa5f607378d23ff0f2 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e1af65c669ebb1666c54576614c01a7f9ffcfff6 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <71a98248c63c535eaa4d4c22f099b68d902006d0 | a5127501c8d30b5728791b1e340284ca5c9cc4bd, e6f4ffe8596947a595c9544e73a73adcb0568b88, ac6985903db047eaff54db929e4bf6b06782788e, c221ed63a2769a0af8bd849dfe25740048f34ef4, eda30846ea54f8ed218468e5480c8305ca645e37, b1dfd6b27df35ef4f87825aa5f607378d23ff0f2, e1af65c669ebb1666c54576614c01a7f9ffcfff6, 71a98248c63c535eaa4d4c22f099b68d902006d0 |
| Linux/Linuxgeneric | 2.6.12 | 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 24, 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: xfrm: clear trailing padding in build_polexpire() build_expire() clears the trailing padding bytes of struct xfrm_user_expire after setting the hard field via memset_after(), but the analogous function build_polexpire() does not do this for struct xfrm_user_polexpire. The padding bytes after the __u8 hard field are left uninitialized from the heap allocation, and are then sent to userspace via netlink multicast to XFRMNLGRP_EXPIRE listeners, leaking kernel heap memory contents. Add the missing memset_after() call, matching build_expire().
Quoted source text, attributed separately from HOL analysis.