CVE-2026-63920

Kernel memory disclosure via rewritten IPv6 header length

Published Jul 19, 2026 · Updated Jul 19, 2026

Out-of-bounds read in Linux Kernel allows local users to disclose kernel memory through crafted IPv6 extension-header processing. ip6_datagram_recv_specific_ctl() trusts a post-parse hdrlen rewrite when sizing put_cmsg(), copying up to 2040 bytes from an eight-byte header. Exploitation requires an unprivileged user and network namespace with nftables access; the resulting slab read can disclose adjacent kernel memory or interrupt the system.

CVSS severity7.1
High
EPSS probability0.17%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Linux Kernel allows local users to disclose kernel memory through crafted IPv6 extension-header processing. ip6_datagram_recv_specific_ctl() trusts a post-parse hdrlen rewrite when sizing put_cmsg(), copying up to 2040 bytes from an eight-byte header. Exploitation requires an unprivileged user and network namespace with nftables access; the resulting slab read can disclose adjacent kernel memory or interrupt the system.

The record

CVE
CVE-2026-63920
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 19, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <08464413e628803bd10cb1df68d0138665f2f885
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0d330eff318c0f44d4fb0ad2c2aef38f87f24c90
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <81394827dfb72772c50d0ae3bdfa094428a5d76d
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <931b4a1f13408c2507719890f78f7227c34a0282
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a29768d56eb3798c052ad3281b05596e695a17af
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a35daeabb433686234b010ebf7b53778dbd6c9b8
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dd433671fef381fdaf7b530c631e6b782d66e224
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <eb18a1b1644e4cad978df2131e2bb9a2e6886992
  9. Affected versionversion=2.6.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <08464413e628803bd10cb1df68d0138665f2f885; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0d330eff318c0f44d4fb0ad2c2aef38f87f24c90; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <81394827dfb72772c50d0ae3bdfa094428a5d76d; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <931b4a1f13408c2507719890f78f7227c34a0282; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a29768d56eb3798c052ad3281b05596e695a17af; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a35daeabb433686234b010ebf7b53778dbd6c9b8; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dd433671fef381fdaf7b530c631e6b782d66e224; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <eb18a1b1644e4cad978df2131e2bb9a2e6886992; version=2.6.12

Published CVSS scores

7.1kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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.

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No observations available

Sep 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1005Data from Local System

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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