CVE-2026-31521module: Fix kernel panic when a symbol st_shndx is out of bounds
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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/20251224005752.201911-1-ihor.solodrai@linux.dev/
- CVSS
- 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 5d16f519b6eb1d071807e57efe0df2baa8d32ad6; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 4bbdb0e48176fd281c2b9a211b110db6fd94e175; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 082f15d2887329e0f43fd3727e69365f5bfe5d2c; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before ec2b22a58073f80739013588af448ff6e2ab906f; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before ef75dc1401d8e797ee51559a0dd0336c225e1776; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 6ba6957c640f58dc8ef046981a045da43e47ea23; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before f9d69d5e7bde2295eb7488a56f094ac8f5383b92 | CNA record |
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
linux linux_kernel linux:linux_kernel | from 2.6.12.1 before 5.15.203; from 5.16 before 6.1.168; from 6.2 before 6.6.131; from 6.7 before 6.12.80; from 6.13 before 6.18.21; from 6.19 before 6.19.11; 2.6.12; 2.6.12; and 5 more ranges | NVD |
References
- https://git.kernel.org/stable/c/5d16f519b6eb1d071807e57efe0df2baa8d32ad6patch
- https://git.kernel.org/stable/c/4bbdb0e48176fd281c2b9a211b110db6fd94e175patch
- https://git.kernel.org/stable/c/082f15d2887329e0f43fd3727e69365f5bfe5d2cpatch
- https://git.kernel.org/stable/c/ec2b22a58073f80739013588af448ff6e2ab906fpatch
- https://git.kernel.org/stable/c/ef75dc1401d8e797ee51559a0dd0336c225e1776patch
- https://git.kernel.org/stable/c/6ba6957c640f58dc8ef046981a045da43e47ea23patch
- https://git.kernel.org/stable/c/f9d69d5e7bde2295eb7488a56f094ac8f5383b92patch
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.