CVE-2025-40236

Information disclosure via uninitialized rxhash fields

Published Dec 4, 2025 · Updated May 11, 2026

Information disclosure in Linux 6.17 through 6.17.5 allows attackers to receive residual data through GSO tunnel metadata. The virtio_net_hdr_tnl_from_skb() helper initializes tunnel metadata without clearing unused hash_value, hash_report, and padding fields. Exposure requires negotiated GSO tunneling and transmission of the generated virtio header; the stated consequence is limited to information passed to the other side.

CVSS severity5.5
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Information disclosure in Linux 6.17 through 6.17.5 allows attackers to receive residual data through GSO tunnel metadata. The virtio_net_hdr_tnl_from_skb() helper initializes tunnel metadata without clearing unused hash_value, hash_report, and padding fields. Exposure requires negotiated GSO tunneling and transmission of the generated virtio header; the stated consequence is limited to information passed to the other side.

The record

CVE
CVE-2025-40236
Published
Dec 4, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Dec 4, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=6.17
  2. Affected versionversion=a2fb4bc4e2a6a031683910d85b278c1d25ae5420 <b2284768c6b32aa224ca7d0ef0741beb434f03aa
  3. Affected versionversion=a2fb4bc4e2a6a031683910d85b278c1d25ae5420 <b625d231c66a6041e98817ffc944bf6e4c45b2e3

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=6.17; version=a2fb4bc4e2a6a031683910d85b278c1d25ae5420 <b2284768c6b32aa224ca7d0ef0741beb434f03aa; version=a2fb4bc4e2a6a031683910d85b278c1d25ae5420 <b625d231c66a6041e98817ffc944bf6e4c45b2e3

Published CVSS scores

5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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