CVE-2026-31521 (GCVE-0-2026-31521)

Vulnerability from cvelistv5 – Published: 2026-04-22 13:54 – Updated: 2026-04-23 15:18
VLAI?
Title
module: Fix kernel panic when a symbol st_shndx is out of bounds
Summary
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/
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 5d16f519b6eb1d071807e57efe0df2baa8d32ad6 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 4bbdb0e48176fd281c2b9a211b110db6fd94e175 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 082f15d2887329e0f43fd3727e69365f5bfe5d2c (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < ec2b22a58073f80739013588af448ff6e2ab906f (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < ef75dc1401d8e797ee51559a0dd0336c225e1776 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 6ba6957c640f58dc8ef046981a045da43e47ea23 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < f9d69d5e7bde2295eb7488a56f094ac8f5383b92 (git)
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    Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 5.15.203 , ≤ 5.15.* (semver)
Unaffected: 6.1.168 , ≤ 6.1.* (semver)
Unaffected: 6.6.131 , ≤ 6.6.* (semver)
Unaffected: 6.12.80 , ≤ 6.12.* (semver)
Unaffected: 6.18.21 , ≤ 6.18.* (semver)
Unaffected: 6.19.11 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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          "value": "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\u0027t 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/"
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}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.