{"cve":"CVE-2026-31521","nvd":{"published":"2026-04-22T14:16:51.930","modified":"2026-10-15T02:19:10.220","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmodule: Fix kernel panic when a symbol st_shndx is out of bounds\n\nThe module loader doesn't check for bounds of the ELF section index in\nsimplify_symbols():\n\n       for (i = 1; i < symsec->sh_size / sizeof(Elf_Sym); i++) {\n\t\tconst char *name = info->strtab + sym[i].st_name;\n\n\t\tswitch (sym[i].st_shndx) {\n\t\tcase SHN_COMMON:\n\n\t\t[...]\n\n\t\tdefault:\n\t\t\t/* Divert to percpu allocation if a percpu var. */\n\t\t\tif (sym[i].st_shndx == info->index.pcpu)\n\t\t\t\tsecbase = (unsigned long)mod_percpu(mod);\n\t\t\telse\n  /** HERE --> **/\t\tsecbase = info->sechdrs[sym[i].st_shndx].sh_addr;\n\t\t\tsym[i].st_value += secbase;\n\t\t\tbreak;\n\t\t}\n\t}\n\nA symbol with an out-of-bounds st_shndx value, for example 0xffff\n(known as SHN_XINDEX or SHN_HIRESERVE), may cause a kernel panic:\n\n  BUG: unable to handle page fault for address: ...\n  RIP: 0010:simplify_symbols+0x2b2/0x480\n  ...\n  Kernel panic - not syncing: Fatal exception\n\nThis can happen when module ELF is legitimately using SHN_XINDEX or\nwhen it is corrupted.\n\nAdd a bounds check in simplify_symbols() to validate that st_shndx is\nwithin the valid range before using it.\n\nThis issue was discovered due to a bug in llvm-objcopy, see relevant\ndiscussion for details [1].\n\n[1] https://lore.kernel.org/linux-modules/20251224005752.201911-1-ihor.solodrai@linux.dev/","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-787"],"references":["https://git.kernel.org/stable/c/082f15d2887329e0f43fd3727e69365f5bfe5d2c","https://git.kernel.org/stable/c/4bbdb0e48176fd281c2b9a211b110db6fd94e175","https://git.kernel.org/stable/c/5d16f519b6eb1d071807e57efe0df2baa8d32ad6","https://git.kernel.org/stable/c/6ba6957c640f58dc8ef046981a045da43e47ea23","https://git.kernel.org/stable/c/ec2b22a58073f80739013588af448ff6e2ab906f"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:30:49.762551342+00:00"},"epss":{"cve":"CVE-2026-31521","score":0.00129,"percentile":0.02497,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}