CVE-2026-53366

Local privilege escalation via undersized IPv4 allocation

Published Jul 16, 2026 · Updated Jul 16, 2026

Heap out-of-bounds write in the Linux Kernel IPv4 UDP path allows local users to gain kernel privileges via crafted corked datagrams. On the paged-allocation branch of __ip_append_data(), fraggap remains in datalen but is omitted from alloclen, so skb_copy_and_csum_bits() copies carried-over bytes past the undersized linear area. IPv4 exploitation requires user namespaces, and a successful overwrite can elevate an unprivileged local user to root or crash the host.

CVSS severity7.8
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Heap out-of-bounds write in the Linux Kernel IPv4 UDP path allows local users to gain kernel privileges via crafted corked datagrams. On the paged-allocation branch of __ip_append_data(), fraggap remains in datalen but is omitted from alloclen, so skb_copy_and_csum_bits() copies carried-over bytes past the undersized linear area. IPv4 exploitation requires user namespaces, and a successful overwrite can elevate an unprivileged local user to root or crash the host.

The record

CVE
CVE-2026-53366
Published
Jul 16, 2026
Updated
Jul 16, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 16, 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=6.0
  2. Affected versionversion=8eb77cc73977d88787b37c92831b1c242e035396 <77798d7be6ef71e72fb6fc8a2901bf74ebc9706f
  3. Affected versionversion=8eb77cc73977d88787b37c92831b1c242e035396 <a9c24eda24bd15f432e37824e6fc440977cb241c
  4. Affected versionversion=8eb77cc73977d88787b37c92831b1c242e035396 <c04d9ece23deb9e26c19f9ca215e98b3295aa1bb
  5. Affected versionversion=8eb77cc73977d88787b37c92831b1c242e035396 <ce494707a9c07f27c219ca67f3e138061f53d9b3
  6. Affected versionversion=8eb77cc73977d88787b37c92831b1c242e035396 <eca856950f7cb1a221e02b99d758409f2c5cec42

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.0; version=8eb77cc73977d88787b37c92831b1c242e035396 <77798d7be6ef71e72fb6fc8a2901bf74ebc9706f; version=8eb77cc73977d88787b37c92831b1c242e035396 <a9c24eda24bd15f432e37824e6fc440977cb241c; version=8eb77cc73977d88787b37c92831b1c242e035396 <c04d9ece23deb9e26c19f9ca215e98b3295aa1bb; version=8eb77cc73977d88787b37c92831b1c242e035396 <ce494707a9c07f27c219ca67f3e138061f53d9b3; version=8eb77cc73977d88787b37c92831b1c242e035396 <eca856950f7cb1a221e02b99d758409f2c5cec42

Published CVSS scores

7.8kernel.orgCVSS:3.1/AV:L/AC:L/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

T1068Exploitation for Privilege Escalation

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