Answer in brief
CVE-2026-31521 records a Medium severity (CVSS 5.5) vulnerability in module: Fix kernel panic when a symbol st_shndx is out of bounds. 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-2026-31521 records a Medium severity (CVSS 5.5) vulnerability in module: Fix kernel panic when a symbol st_shndx is out of bounds. 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 <5d16f519b6eb1d071807e57efe0df2baa8d32ad6 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4bbdb0e48176fd281c2b9a211b110db6fd94e175 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <082f15d2887329e0f43fd3727e69365f5bfe5d2c || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ec2b22a58073f80739013588af448ff6e2ab906f || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ef75dc1401d8e797ee51559a0dd0336c225e1776 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6ba6957c640f58dc8ef046981a045da43e47ea23 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f9d69d5e7bde2295eb7488a56f094ac8f5383b92 | 5d16f519b6eb1d071807e57efe0df2baa8d32ad6, 4bbdb0e48176fd281c2b9a211b110db6fd94e175, 082f15d2887329e0f43fd3727e69365f5bfe5d2c, ec2b22a58073f80739013588af448ff6e2ab906f, ef75dc1401d8e797ee51559a0dd0336c225e1776, 6ba6957c640f58dc8ef046981a045da43e47ea23, f9d69d5e7bde2295eb7488a56f094ac8f5383b92 |
| 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 22, 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: module: Fix kernel panic when a symbol st_shndx is out of bounds The module loader doesn't check for bounds of the ELF section index in simplify_symbols(): for (i = 1; i < symsec->sh_size / sizeof(Elf_Sym); i++) { const char *name = info->strtab + sym[i].st_name; switch (sym[i].st_shndx) { case SHN_COMMON: [...] default: /* Divert to percpu allocation if a percpu var. */ if (sym[i].st_shndx == info->index.pcpu) secbase = (unsigned long)mod_percpu(mod); else /** HERE --> **/ secbase = info->sechdrs[sym[i].st_shndx].sh_addr; sym[i].st_value += secbase; break; } } A symbol with an out-of-bounds st_shndx value, for example 0xffff (known as SHN_XINDEX or SHN_HIRESERVE), may cause a kernel panic: BUG: unable to handle page fault for address: ... RIP: 0010:simplify_symbols+0x2b2/0x480 ... Kernel panic - not syncing: Fatal exception This can happen when module ELF is legitimately using SHN_XINDEX or when it is corrupted. Add a bounds check in simplify_symbols() to validate that st_shndx is within the valid range before using it. This issue was discovered due to a bug in llvm-objcopy, see relevant discussion for details [1]. [1] https://lore.kernel.org/linux-modules/[email protected]/
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 <5d16f519b6eb1d071807e57efe0df2baa8d32ad6 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4bbdb0e48176fd281c2b9a211b110db6fd94e175 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <082f15d2887329e0f43fd3727e69365f5bfe5d2c || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ec2b22a58073f80739013588af448ff6e2ab906f || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ef75dc1401d8e797ee51559a0dd0336c225e1776 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6ba6957c640f58dc8ef046981a045da43e47ea23 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f9d69d5e7bde2295eb7488a56f094ac8f5383b92 | 5d16f519b6eb1d071807e57efe0df2baa8d32ad6, 4bbdb0e48176fd281c2b9a211b110db6fd94e175, 082f15d2887329e0f43fd3727e69365f5bfe5d2c, ec2b22a58073f80739013588af448ff6e2ab906f, ef75dc1401d8e797ee51559a0dd0336c225e1776, 6ba6957c640f58dc8ef046981a045da43e47ea23, f9d69d5e7bde2295eb7488a56f094ac8f5383b92 |
| 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 22, 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: module: Fix kernel panic when a symbol st_shndx is out of bounds The module loader doesn't check for bounds of the ELF section index in simplify_symbols(): for (i = 1; i < symsec->sh_size / sizeof(Elf_Sym); i++) { const char *name = info->strtab + sym[i].st_name; switch (sym[i].st_shndx) { case SHN_COMMON: [...] default: /* Divert to percpu allocation if a percpu var. */ if (sym[i].st_shndx == info->index.pcpu) secbase = (unsigned long)mod_percpu(mod); else /** HERE --> **/ secbase = info->sechdrs[sym[i].st_shndx].sh_addr; sym[i].st_value += secbase; break; } } A symbol with an out-of-bounds st_shndx value, for example 0xffff (known as SHN_XINDEX or SHN_HIRESERVE), may cause a kernel panic: BUG: unable to handle page fault for address: ... RIP: 0010:simplify_symbols+0x2b2/0x480 ... Kernel panic - not syncing: Fatal exception This can happen when module ELF is legitimately using SHN_XINDEX or when it is corrupted. Add a bounds check in simplify_symbols() to validate that st_shndx is within the valid range before using it. This issue was discovered due to a bug in llvm-objcopy, see relevant discussion for details [1]. [1] https://lore.kernel.org/linux-modules/[email protected]/
Quoted source text, attributed separately from HOL analysis.