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CVE Record

CVE-2026-64082: riscv: Fix register corruption from uninitialized cregs on error

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.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel bug affecting RISC-V paths where a failed user-memory copy can still overwrite a task's saved CPU registers with uninitialized kernel stack data. That can corrupt process state and may expose sensitive kernel stack contents. The CVSS score is high because exploitation requires local privileges but can affect confidentiality, integrity, and availability.

Executive priority

Treat as high priority for RISC-V Linux environments, especially multi-user, container-hosting, or embedded platforms. It is not currently sourced as actively exploited, but the impact includes possible information disclosure and process state corruption inside the kernel boundary.

Technical view

Two RISC-V compatibility paths call cregs_to_regs() after failed user copies: compat_riscv_gpr_set() after user_regset_copyin(), and compat_restore_sigcontext() after __copy_from_user(). Because cregs is uninitialized stack data, failure can write unintended values into pt_regs, causing register corruption and possible kernel stack disclosure. The fix is to convert registers only after successful copy.

Likely exposure

Exposure is most relevant to Linux deployments on RISC-V using affected kernel versions or downstream kernels missing the referenced stable fixes. The bundle's affected version data is limited and partly ambiguous, so validate against vendor kernel advisories and patch changelogs.

Exploitation context

The CVE is not listed as KEV in the supplied bundle, and no source here reports active exploitation. The CVSS vector indicates local, low-complexity exploitation with required low privileges and no user interaction.

Researcher notes

The issue is error-path dependent: failed copyin operations still trigger cregs_to_regs() with uninitialized cregs. Research should focus on patch presence and reachable RISC-V compat/signal-return paths, without assuming remote exposure or confirmed exploitation from the supplied evidence.

Mitigation direction

  • Apply Linux kernel updates containing the referenced stable fixes.
  • Prioritize RISC-V Linux systems and downstream kernels with backported compatibility code.
  • Check distribution and appliance vendor advisories for exact patched package versions.
  • Reduce unnecessary local shell or process execution access on affected hosts.
  • Monitor kernel vendor updates because source version ranges are incomplete.

Validation and detection

  • Inventory Linux systems running on RISC-V architecture.
  • Confirm the running kernel includes commits 9e020156833f or 6ebcbb53fc9b, or vendor backports.
  • Review distribution kernel changelogs for CVE-2026-64082.
  • Verify patch status in golden images, appliances, and embedded builds.
  • Check whether untrusted local users or workloads can execute on affected hosts.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2026-64082 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
0ADP providers
3Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2026-64082Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux7383ee05314be58f8f9f018ee0ac53bef3808aea, 7383ee05314be58f8f9f018ee0ac53bef3808aeaunaffected
LinuxLinux5.19, 0, 7.0.11, 7.1affected
Weakness

CWE details

No CWE listed

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