CVE-2026-80840Network attack vectorHinoki check available

Kernel memory corruption via stale control block

Published Sep 4, 2026 · Updated Sep 4, 2026

Out-of-bounds write in the Linux kernel allows remote attackers to corrupt kernel memory via crafted SRv6 IPIP traffic. End.DX4, End.DT4, and the IPv4 arm of End.DT46 bypass ip_rcv_core() after decapsulation, leaving outer-packet IP6CB bytes in shared skb->cb storage; __ip_options_echo() then treats those stale bytes as IPv4 option metadata and copies 255 bytes into a 40-byte area. Exposure requires an SRv6 local action that decapsulates attacker-controlled IPv4-in-IPv6 traffic and reaches the TCP SYN path.

CVSS severityUnavailable
Unscored
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Out-of-bounds write in the Linux kernel allows remote attackers to corrupt kernel memory via crafted SRv6 IPIP traffic. End.DX4, End.DT4, and the IPv4 arm of End.DT46 bypass ip_rcv_core() after decapsulation, leaving outer-packet IP6CB bytes in shared skb->cb storage; __ip_options_echo() then treats those stale bytes as IPv4 option metadata and copies 255 bytes into a 40-byte area. Exposure requires an SRv6 local action that decapsulates attacker-controlled IPv4-in-IPv6 traffic and reaches the TCP SYN path.

The record

CVE
CVE-2026-80840
Published
Sep 4, 2026
Updated
Sep 4, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 4, 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=4.14
  2. Affected versionversion=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <0e3f01fe2e704e76af4385b8a1742641885a191c
  3. Affected versionversion=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <10fd1a8f58ac619a9e251f2858e2e2c8fd6cd667
  4. Affected versionversion=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <3e4476e58343fb8f2fffced9e22d935376b17aaf
  5. Affected versionversion=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <44930446dde45a7a90fe1446fa38eb0e2c561646
  6. Affected versionversion=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <9039e4f3e1c0ffe2b575b655b3f58fdd10f7e40c
  7. Affected versionversion=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <bf1c1151560d11036a144d917fa4c131831342d7
  8. Affected versionversion=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <eb0f422487228e140f3d609b032ac61aedcab8fa
  9. Affected versionversion=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <f4be3b391265e24c7720fc867c50062b436acf33
  10. Affected versionversion=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <f52f1e75716d2ee49e013edf204ac92337c72fd8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.14; version=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <0e3f01fe2e704e76af4385b8a1742641885a191c; version=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <10fd1a8f58ac619a9e251f2858e2e2c8fd6cd667; version=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <3e4476e58343fb8f2fffced9e22d935376b17aaf; version=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <44930446dde45a7a90fe1446fa38eb0e2c561646; version=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <9039e4f3e1c0ffe2b575b655b3f58fdd10f7e40c; version=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <bf1c1151560d11036a144d917fa4c131831342d7; version=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <eb0f422487228e140f3d609b032ac61aedcab8fa; version=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <f4be3b391265e24c7720fc867c50062b436acf33; version=891ef8dd2a8d14e4e73a81dcdb135b574c57f556 <f52f1e75716d2ee49e013edf204ac92337c72fd8

Published CVSS scores

No CVSS assessment is available in this record.

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)
Vectornetwork
Privilegesunauthenticated
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo