CVE-2025-39718

Guest kernel memory corruption via unchecked packet length

Published Sep 5, 2025 · Updated Sep 5, 2025

Out-of-bounds write in affected Linux kernel branches allows attackers controlling the virtualization host to corrupt guest kernel memory. virtio_vsock_skb_rx_put() passes the unvalidated packet-header length to skb_put() after validating only the virtqueue buffer size. The host must supply a header length larger than the received buffer; the public record establishes memory corruption but no demonstrated crash or code execution.

CVSS severity8.4
High
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in affected Linux kernel branches allows attackers controlling the virtualization host to corrupt guest kernel memory. virtio_vsock_skb_rx_put() passes the unvalidated packet-header length to skb_put() after validating only the virtqueue buffer size. The host must supply a header length larger than the received buffer; the public record establishes memory corruption but no demonstrated crash or code execution.

The record

CVE
CVE-2025-39718
Published
Sep 5, 2025
Updated
Sep 5, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-787, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 5, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 5, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.3
  2. Affected versionversion=71dc9ec9ac7d3eee785cdc986c3daeb821381e20 <0dab92484474587b82e8e0455839eaf5ac7bf894
  3. Affected versionversion=71dc9ec9ac7d3eee785cdc986c3daeb821381e20 <676f03760ca1d69c2470cef36c44dc152494b47c
  4. Affected versionversion=71dc9ec9ac7d3eee785cdc986c3daeb821381e20 <ee438c492b2e0705d819ac0e25d04fae758d8f8f
  5. Affected versionversion=71dc9ec9ac7d3eee785cdc986c3daeb821381e20 <faf332a10372390ce65d0b803888f4b25a388335
  6. Affected versionversion=baddcc2c71572968cdaeee1c4ab3dc0ad90fa765 <969b06bd8b7560efb100a34227619e7d318fbe05

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.3; version=71dc9ec9ac7d3eee785cdc986c3daeb821381e20 <0dab92484474587b82e8e0455839eaf5ac7bf894; version=71dc9ec9ac7d3eee785cdc986c3daeb821381e20 <676f03760ca1d69c2470cef36c44dc152494b47c; version=71dc9ec9ac7d3eee785cdc986c3daeb821381e20 <ee438c492b2e0705d819ac0e25d04fae758d8f8f; version=71dc9ec9ac7d3eee785cdc986c3daeb821381e20 <faf332a10372390ce65d0b803888f4b25a388335; version=baddcc2c71572968cdaeee1c4ab3dc0ad90fa765 <969b06bd8b7560efb100a34227619e7d318fbe05

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
8.4Linux kernelCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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