Vulnerability-Lookup

GHSA-87CJ-725F-6HR5

Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-09-02 15:34

Details

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.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-64082"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-908"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-19T16:17:48Z",
    "severity": "HIGH"
  },
  "details": "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.",
  "id": "GHSA-87cj-725f-6hr5",
  "modified": "2026-09-02T15:34:20Z",
  "published": "2026-07-19T18:31:51Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64082"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0599aa23734c48de9bce36d043a9ec90c23945a1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2a7d1daf2674fe7d5b1cc99a4e3b5f0f72d5958f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/66dedb6028c3df6c6a3372dd935b823917e150d5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6ebcbb53fc9bc30843054ed99fd60b8e542628f4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9e020156833f1ad0d425a1e3d85b65639f1c1c50"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f2d88b0d7aebfa4643fc58bbae57210c6daff9c6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-64082 (GCVE-0-2026-64082)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:39 – Updated: 2026-09-02 12:49

Title

riscv: Fix register corruption from uninitialized cregs on error

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.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

6 references

URL	Tags
https://git.kernel.org/stable/c/f2d88b0d7aebfa464…
https://git.kernel.org/stable/c/66dedb6028c3df6c6…
https://git.kernel.org/stable/c/2a7d1daf2674fe7d5…
https://git.kernel.org/stable/c/0599aa23734c48de9…
https://git.kernel.org/stable/c/9e020156833f1ad0d…
https://git.kernel.org/stable/c/6ebcbb53fc9bc3084…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 7383ee05314be58f8f9f018ee0ac53bef3808aea , < f2d88b0d7aebfa4643fc58bbae57210c6daff9c6 (git) Affected: 7383ee05314be58f8f9f018ee0ac53bef3808aea , < 66dedb6028c3df6c6a3372dd935b823917e150d5 (git) Affected: 7383ee05314be58f8f9f018ee0ac53bef3808aea , < 2a7d1daf2674fe7d5b1cc99a4e3b5f0f72d5958f (git) Affected: 7383ee05314be58f8f9f018ee0ac53bef3808aea , < 0599aa23734c48de9bce36d043a9ec90c23945a1 (git) Affected: 7383ee05314be58f8f9f018ee0ac53bef3808aea , < 9e020156833f1ad0d425a1e3d85b65639f1c1c50 (git) Affected: 7383ee05314be58f8f9f018ee0ac53bef3808aea , < 6ebcbb53fc9bc30843054ed99fd60b8e542628f4 (git)
Linux	Linux	Affected: 5.19 Unaffected: 0 , < 5.19 (semver) Unaffected: 6.1.187 , ≤ 6.1.* (semver) Unaffected: 6.6.156 , ≤ 6.6.* (semver) Unaffected: 6.12.108 , ≤ 6.12.* (semver) Unaffected: 6.18.49 , ≤ 6.18.* (semver) Unaffected: 7.0.11 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix)

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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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          "vendor": "Linux",
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              "versionType": "git"
            },
            {
              "lessThan": "66dedb6028c3df6c6a3372dd935b823917e150d5",
              "status": "affected",
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              "versionType": "git"
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            {
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              "versionType": "git"
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              "versionType": "git"
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              "lessThan": "9e020156833f1ad0d425a1e3d85b65639f1c1c50",
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              "versionType": "git"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "versionType": "semver"
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              "status": "unaffected",
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              "versionType": "semver"
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            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
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              "versionType": "semver"
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            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
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              "versionType": "semver"
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              "versionType": "semver"
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              "status": "unaffected",
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              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
                {
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                },
                {
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          "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."
        }
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            "baseScore": 7.8,
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            "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",
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        },
        {
          "url": "https://git.kernel.org/stable/c/6ebcbb53fc9bc30843054ed99fd60b8e542628f4"
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      "title": "riscv: Fix register corruption from uninitialized cregs on error",
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    "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"
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  "dataType": "CVE_RECORD",
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

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GHSA-87CJ-725F-6HR5

CVE-2026-64082 (GCVE-0-2026-64082)

Tags

Sightings

Nomenclature