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CVE Record

CVE-2026-31730: misc: fastrpc: possible double-free of cctx->remote_heap

In the Linux kernel, the following vulnerability has been resolved: misc: fastrpc: possible double-free of cctx->remote_heap fastrpc_init_create_static_process() may free cctx->remote_heap on the err_map path but does not clear the pointer. Later, fastrpc_rpmsg_remove() frees cctx->remote_heap again if it is non-NULL, which can lead to a double-free if the INIT_CREATE_STATIC ioctl hits the error path and the rpmsg device is subsequently removed/unbound. Clear cctx->remote_heap after freeing it in the error path to prevent the later cleanup from freeing it again. This issue was found by an in-house analysis workflow that extracts AST-based information and runs static checks, with LLM assistance for triage, and was confirmed by manual code review. No hardware testing was performed.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A flaw in Linux FastRPC cleanup can free the same memory twice after a specific error and later device removal. A local low-privilege user could potentially cause kernel memory corruption, threatening system confidentiality, integrity, and availability. Practical exploitability remains unconfirmed.

Executive priority

Schedule expedited remediation for affected systems exposing FastRPC to untrusted local users. Although exploitation is not reported, successful abuse could compromise the entire host. Systems without FastRPC exposure are lower priority, but exact build status should still be verified because the supplied version mapping is unclear.

Technical view

fastrpc_init_create_static_process() frees cctx->remote_heap on the err_map path without clearing the pointer. fastrpc_rpmsg_remove() can later free it again when the rpmsg device is removed or unbound. The published fix sets the pointer to NULL after the first free.

Likely exposure

Exposure is limited to Linux systems containing affected FastRPC code. Triggering requires local access, the INIT_CREATE_STATIC ioctl error path, and subsequent rpmsg removal or unbinding. The supplied version information is ambiguous, so verify exact distribution kernels against vendor guidance and the listed stable commits.

Exploitation context

The CVSS score is 7.8 with local, low-complexity, low-privilege access and no user interaction. The source bundle marks this CVE as absent from KEV and provides no evidence of active exploitation. Static analysis and manual review confirmed the flaw, but no hardware testing was performed.

Researcher notes

The trigger is a lifecycle sequence: failed static-process creation leaves a dangling remote_heap pointer, then removal cleanup frees it again. Impact is inferred from kernel double-free behavior and the CVSS assessment; the sources do not demonstrate exploitation, reliability, or hardware reproduction. Avoid treating every listed Linux version as conclusively affected without build-level verification.

Mitigation direction

  • Apply a vendor kernel update containing the applicable listed stable fix.
  • Confirm the fix clears cctx->remote_heap immediately after freeing it on the error path.
  • Prioritize systems where untrusted local users can access FastRPC functionality.
  • Consult distribution guidance because the supplied affected-version data is not sufficiently precise.

Validation and detection

  • Inventory kernel versions and distribution build identifiers on systems using FastRPC.
  • Check each kernel package for inclusion of the applicable listed stable commit.
  • Verify whether FastRPC and relevant rpmsg functionality are enabled and accessible locally.
  • Review kernel logs for FastRPC failures, memory corruption, crashes, or unexpected rpmsg removal.
  • Use vendor-supported testing to confirm normal FastRPC behavior after updating.
Prepared
Confidence
high
Sources
7

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2026-31730 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
6Source 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-2026-31730Attack 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
LinuxLinux0871561055e666da421d779397efcc1e5e964cab, 0871561055e666da421d779397efcc1e5e964cab, 0871561055e666da421d779397efcc1e5e964cab, 0871561055e666da421d779397efcc1e5e964cab, 0871561055e666da421d779397efcc1e5e964cabunaffected
LinuxLinux6.2, 0, 6.6.134, 6.12.81, 6.18.22, 6.19.12, 7.0affected
Weakness

CWE details

No CWE listed

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