CVE-2026-64082 (GCVE-0-2026-64082)
Vulnerability from cvelistv5
Published
2026-07-19 15:39
Modified
2026-09-02 12:49
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: riscv: Fix register corruption from uninitialized cregs on error compat_riscv_gpr_set() calls cregs_to_regs() unconditionally, even when user_regset_copyin() fails. Since cregs is an uninitialized stack variable, a copyin failure causes uninitialized stack data to be written into the target task's pt_regs, corrupting its register state and potentially leaking kernel stack contents. compat_restore_sigcontext() has the same issue: it calls cregs_to_regs() even when __copy_from_user() fails, leading to the same corruption of the signal-returning task's register state on error. Only call cregs_to_regs() when the user copy succeeds.
References
Impacted products
Vendor Product Version
Linux Linux Version: 7383ee05314be58f8f9f018ee0ac53bef3808aea
Version: 7383ee05314be58f8f9f018ee0ac53bef3808aea
Version: 7383ee05314be58f8f9f018ee0ac53bef3808aea
Version: 7383ee05314be58f8f9f018ee0ac53bef3808aea
Version: 7383ee05314be58f8f9f018ee0ac53bef3808aea
Version: 7383ee05314be58f8f9f018ee0ac53bef3808aea
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/riscv/kernel/compat_signal.c",
            "arch/riscv/kernel/ptrace.c"
          ],
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          "product": "Linux",
          "programFiles": [
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            "arch/riscv/kernel/ptrace.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "5.19"
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              "status": "unaffected",
              "version": "0",
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              "version": "6.6.156",
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              "status": "unaffected",
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              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.49",
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              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.187",
                  "versionStartIncluding": "5.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nriscv: Fix register corruption from uninitialized cregs on error\n\ncompat_riscv_gpr_set() calls cregs_to_regs() unconditionally, even when\nuser_regset_copyin() fails. Since cregs is an uninitialized stack\nvariable, a copyin failure causes uninitialized stack data to be written\ninto the target task\u0027s pt_regs, corrupting its register state and\npotentially leaking kernel stack contents.\n\ncompat_restore_sigcontext() has the same issue: it calls cregs_to_regs()\neven when __copy_from_user() fails, leading to the same corruption of\nthe signal-returning task\u0027s register state on error.\n\nOnly call cregs_to_regs() when the user copy succeeds."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The bug is only reachable through local kernel interfaces\u2014compat_rt_sigreturn and ptrace(PTRACE_SETREGSET)\u2014with no network, adjacent-radio, or physical-device code path involved.\nAC:L - An attacker can reliably force the user copy to fail by racing munmap/mprotect against sigreturn or ptrace SETREGSET after access_ok, controlling both sides of the TOCTOU window.\nPR:L - The lowest-privilege path is compat_rt_sigreturn, callable by any unprivileged 32-bit compat process on a CONFIG_COMPAT RISC-V system without capabilities or root.\nUI:N - Exploitation requires no victim interaction; a local attacker corrupts their own task\u2019s registers via rt_sigreturn or a tracee they already control as parent/tracer.\nS:U - Impact is confined to kernel register-state corruption and information disclosure within the same OS security boundary, not a VM escape or cross-authority sandbox breakout.\nC:H - On copy failure, uninitialized kernel stack data (up to the full compat_user_regs_struct) is written into pt_regs, leaking kernel memory contents into user-observable registers.\nI:H - The corruption overwrites all general-purpose registers in pt_regs\u2014including program counter, stack pointer, and return address\u2014constituting memory corruption exploitable for control-flow hijacking.\nA:H - Corrupted pt_regs reliably cause faults, SIGSEGV delivery, or erratic kernel/user execution, and the condition is repeatable for persistent denial of service."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-02T12:49:41.782Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f2d88b0d7aebfa4643fc58bbae57210c6daff9c6"
        },
        {
          "url": "https://git.kernel.org/stable/c/66dedb6028c3df6c6a3372dd935b823917e150d5"
        },
        {
          "url": "https://git.kernel.org/stable/c/2a7d1daf2674fe7d5b1cc99a4e3b5f0f72d5958f"
        },
        {
          "url": "https://git.kernel.org/stable/c/0599aa23734c48de9bce36d043a9ec90c23945a1"
        },
        {
          "url": "https://git.kernel.org/stable/c/9e020156833f1ad0d425a1e3d85b65639f1c1c50"
        },
        {
          "url": "https://git.kernel.org/stable/c/6ebcbb53fc9bc30843054ed99fd60b8e542628f4"
        }
      ],
      "title": "riscv: Fix register corruption from uninitialized cregs on error",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64082",
    "datePublished": "2026-07-19T15:39:54.074Z",
    "dateReserved": "2026-07-19T07:54:57.031Z",
    "dateUpdated": "2026-09-02T12:49:41.782Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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