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Review reviewHigh

CVE-2026-64456

Linux

In the Linux kernel, the following vulnerability has been resolved: hwrng: virtio: clamp device-reported used.len at copy_data() random_recv_done() stores the device-reported used.len directly into vi->data_avail. copy_data() then indexes vi->data[] using vi->data_idx (advanced by previous copy_data() calls) and issues a memcpy() without re-validating either value against the posted buffer size sizeof(vi->data) (SMP_CACHE_BYTES bytes, typically 32 or 64). A malicious or buggy virtio-rng backend can set used.len beyond sizeof(vi->data), steering the memcpy() past the end of the inline array...

CVSS
7.7
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.25
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 7.7

Vulnerability overview

In the Linux kernel, the following vulnerability has been resolved: hwrng: virtio: clamp device-reported used.len at copy_data() random_recv_done() stores the device-reported used.len directly into vi->data_avail. copy_data() then indexes vi->data[] using vi->data_idx (advanced by previous copy_data() calls) and issues a memcpy() without re-validating either value against the posted buffer size sizeof(vi->data) (SMP_CACHE_BYTES bytes, typically 32 or 64). A malicious or buggy virtio-rng backend can set used.len beyond sizeof(vi->data), steering the memcpy() past the end of the inline array...

Affected product and versions

Product
Linux
Affected versions
>= f7f510ec195781c857ab76366a3e1c59e1caae42 < 3aa3e89cf80721c8d382b4c1a2b70a0449dad4a5, >= f7f510ec195781c857ab76366a3e1c59e1caae42 < 63335e7b638ae70028ae285bb95153874a8bc852, >= f7f510ec195781c857ab76366a3e1c59e1caae42 < 2e788948ff2a13358a303af112497a63201c5739, >= f7f510ec195781c857ab76366a3e1c59e1caae42 < fde19b0d4eeabae042519313c843fe6f27d41e9d, >= f7f510ec195781c857ab76366a3e1c59e1caae42 < 81dd21b5f0c299cc7b5bf84f04a61938559d20e6, >= f7f510ec195781c857ab76366a3e1c59e1caae42 < 285e17c44e3873a73460f294acbd64018ff64385, >= f7f510ec195781c857ab76366a3e1c59e1caae42 < 92d5736a62040ec1cfff23ea57e6599301690ad5, >= f7f510ec195781c857ab76366a3e1c59e1caae42 < e3046eeada299f917a8ad883af4434bfb86556b1, >= 2.6.26
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
CWE
Not available
CVE-2026-64456 — Linux | SECUFOCUS NOW