CVE-2026-63919Network attack vector

Kernel crash via stale network namespace pointer

Published Jul 19, 2026 · Updated Jul 19, 2026

Use-after-free in the Linux Kernel XFRM input component allows remote authenticated users to crash affected systems through IPsec traffic. xfrm_trans_queue_net() stores a network-namespace pointer in skb->cb without taking a reference, so xfrm_trans_reinject() can dereference it after teardown. Triggering requires configured IPsec plus CAP_NET_ADMIN to manage XFRM state and network-namespace lifetime; kernel.org also scores confidentiality and integrity effects but does not describe a privilege-escalation primitive.

CVSS severity8.8
High
EPSS probability0.65%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux Kernel XFRM input component allows remote authenticated users to crash affected systems through IPsec traffic. xfrm_trans_queue_net() stores a network-namespace pointer in skb->cb without taking a reference, so xfrm_trans_reinject() can dereference it after teardown. Triggering requires configured IPsec plus CAP_NET_ADMIN to manage XFRM state and network-namespace lifetime; kernel.org also scores confidentiality and integrity effects but does not describe a privilege-escalation primitive.

The record

CVE
CVE-2026-63919
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-911, T1499
Attack vector
network
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=5.6
  2. Affected versionversion=7b3801927e52f8621de311277f7fc727635019e7 <2df7059a18afb7d3aee6c36cad5d371c198111d4
  3. Affected versionversion=7b3801927e52f8621de311277f7fc727635019e7 <48ce101cd630d6745b6923b5bad8358bc4c119da
  4. Affected versionversion=7b3801927e52f8621de311277f7fc727635019e7 <55ddfc41451f01c588089cd74957a05311b6f202
  5. Affected versionversion=7b3801927e52f8621de311277f7fc727635019e7 <7ee59eda8820b758ed29e1cd3222359c7b97302c
  6. Affected versionversion=7b3801927e52f8621de311277f7fc727635019e7 <8dfabcba6a943a7a02ebe1e1637c361ba96acbaa
  7. Affected versionversion=7b3801927e52f8621de311277f7fc727635019e7 <9f67a36e91bb50d358760f381f233913fe5c09f8
  8. Affected versionversion=7b3801927e52f8621de311277f7fc727635019e7 <9f7ebb45a83afc3216e855e57d51bb4bc9b5232e
  9. Affected versionversion=7b3801927e52f8621de311277f7fc727635019e7 <c16f74dc1d75d0e2e7670076d5375deda110ebeb

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.6; version=7b3801927e52f8621de311277f7fc727635019e7 <2df7059a18afb7d3aee6c36cad5d371c198111d4; version=7b3801927e52f8621de311277f7fc727635019e7 <48ce101cd630d6745b6923b5bad8358bc4c119da; version=7b3801927e52f8621de311277f7fc727635019e7 <55ddfc41451f01c588089cd74957a05311b6f202; version=7b3801927e52f8621de311277f7fc727635019e7 <7ee59eda8820b758ed29e1cd3222359c7b97302c; version=7b3801927e52f8621de311277f7fc727635019e7 <8dfabcba6a943a7a02ebe1e1637c361ba96acbaa; version=7b3801927e52f8621de311277f7fc727635019e7 <9f67a36e91bb50d358760f381f233913fe5c09f8; version=7b3801927e52f8621de311277f7fc727635019e7 <9f7ebb45a83afc3216e855e57d51bb4bc9b5232e; version=7b3801927e52f8621de311277f7fc727635019e7 <c16f74dc1d75d0e2e7670076d5375deda110ebeb

Published CVSS scores

8.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.0Red HatCVSS:3.1/AV:L/AC:H/PR:L/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.

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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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-911Improper Update of Reference Count
T1499Endpoint Denial of Service

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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