CVE-2023-53500

Memory disclosure and crash via stale control block

Published Oct 1, 2025 · Updated Aug 5, 2026

Use-after-free in affected Linux kernel releases allows local users to disclose kernel memory and interrupt IPv6 IPsec traffic. On the xfrm IPv6 transmit path, decode_session6 reads IP6CB(skb)->nhoff after an sfb qdisc overwrites the reused skb control block, treating stale data as an offset. Exploitation requires CAP_NET_ADMIN in a user namespace to create an xfrm interface, attach sfb, and send IPv6 packets; the read can panic the kernel or drop tunnel traffic.

CVSS severity7.3
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

Use-after-free in affected Linux kernel releases allows local users to disclose kernel memory and interrupt IPv6 IPsec traffic. On the xfrm IPv6 transmit path, decode_session6 reads IP6CB(skb)->nhoff after an sfb qdisc overwrites the reused skb control block, treating stale data as an offset. Exploitation requires CAP_NET_ADMIN in a user namespace to create an xfrm interface, attach sfb, and send IPv6 packets; the read can panic the kernel or drop tunnel traffic.

The record

CVE
CVE-2023-53500
Published
Oct 1, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 1, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record 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=3.19
  2. Affected versionversion=f855691975bb06373a98711e4cfe2c224244b536 <0d27567fde5be5f0edc2db5c110142b7915b8fa8
  3. Affected versionversion=f855691975bb06373a98711e4cfe2c224244b536 <44b3d40967009304617a7a6486490c1d6c12f899
  4. Affected versionversion=f855691975bb06373a98711e4cfe2c224244b536 <53223f2ed1ef5c90dad814daaaefea4e68a933c8
  5. Affected versionversion=f855691975bb06373a98711e4cfe2c224244b536 <86f15300a22656db3fa8c8967defbcd24fac4d37
  6. Affected versionversion=f855691975bb06373a98711e4cfe2c224244b536 <bafa236380816b41b2c4c6970d9067fefa4a6c9e
  7. Affected versionversion=f855691975bb06373a98711e4cfe2c224244b536 <da4cbaa75ed088b6d70db77b9103a27e2359e243
  8. Affected versionversion=f855691975bb06373a98711e4cfe2c224244b536 <db0e50741f0387f388e9ec824ea7ae8456554d5b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.19; version=f855691975bb06373a98711e4cfe2c224244b536 <0d27567fde5be5f0edc2db5c110142b7915b8fa8; version=f855691975bb06373a98711e4cfe2c224244b536 <44b3d40967009304617a7a6486490c1d6c12f899; version=f855691975bb06373a98711e4cfe2c224244b536 <53223f2ed1ef5c90dad814daaaefea4e68a933c8; version=f855691975bb06373a98711e4cfe2c224244b536 <86f15300a22656db3fa8c8967defbcd24fac4d37; version=f855691975bb06373a98711e4cfe2c224244b536 <bafa236380816b41b2c4c6970d9067fefa4a6c9e; version=f855691975bb06373a98711e4cfe2c224244b536 <da4cbaa75ed088b6d70db77b9103a27e2359e243; version=f855691975bb06373a98711e4cfe2c224244b536 <db0e50741f0387f388e9ec824ea7ae8456554d5b

Published CVSS scores

7.3Linux Kernel CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
7.8NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.0Amazon LinuxCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application 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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