{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2"
            },
            {
              "fixed": "5d16f519b6eb1d071807e57efe0df2baa8d32ad6"
            },
            {
              "fixed": "4bbdb0e48176fd281c2b9a211b110db6fd94e175"
            },
            {
              "fixed": "082f15d2887329e0f43fd3727e69365f5bfe5d2c"
            },
            {
              "fixed": "ec2b22a58073f80739013588af448ff6e2ab906f"
            },
            {
              "fixed": "ef75dc1401d8e797ee51559a0dd0336c225e1776"
            },
            {
              "fixed": "6ba6957c640f58dc8ef046981a045da43e47ea23"
            },
            {
              "fixed": "f9d69d5e7bde2295eb7488a56f094ac8f5383b92"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.6.12"
            },
            {
              "fixed": "5.15.203"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.168"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.131"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.80"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.21"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "6.19.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31521.json"
  },
  "details": "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 \u003c symsec-\u003esh_size / sizeof(Elf_Sym); i++) {\n\t\tconst char *name = info-\u003estrtab + 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-\u003eindex.pcpu)\n\t\t\t\tsecbase = (unsigned long)mod_percpu(mod);\n\t\t\telse\n  /** HERE --\u003e **/\t\tsecbase = info-\u003esechdrs[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/",
  "id": "CVE-2026-31521",
  "modified": "2026-07-08T05:36:29.626256634Z",
  "published": "2026-04-22T13:54:36.211Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/082f15d2887329e0f43fd3727e69365f5bfe5d2c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4bbdb0e48176fd281c2b9a211b110db6fd94e175"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5d16f519b6eb1d071807e57efe0df2baa8d32ad6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6ba6957c640f58dc8ef046981a045da43e47ea23"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ec2b22a58073f80739013588af448ff6e2ab906f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ef75dc1401d8e797ee51559a0dd0336c225e1776"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f9d69d5e7bde2295eb7488a56f094ac8f5383b92"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31521.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31521"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "summary": "module: Fix kernel panic when a symbol st_shndx is out of bounds"
}