CVE-2026-46300Public exploit

Local root escalation via shared-frag marker loss

Published May 23, 2026 · Updated May 23, 2026

Privilege escalation in the Linux kernel allows local users to gain root access through ESP-in-TCP page-cache corruption. skb_try_coalesce() transfers page-backed fragments without carrying SKBFL_SHARED_FRAG, so ESP input skips copy-on-write and decrypts attacker-controlled data directly into cached file pages. Exploitation requires local low-privileged execution, unprivileged user and network namespaces, and the ESP-in-TCP path; the public chain overwrites the cached /usr/bin/su image and launches a root shell.

CVSS severity7.8
High
EPSS probability9.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Privilege escalation in the Linux kernel allows local users to gain root access through ESP-in-TCP page-cache corruption. skb_try_coalesce() transfers page-backed fragments without carrying SKBFL_SHARED_FRAG, so ESP input skips copy-on-write and decrypts attacker-controlled data directly into cached file pages. Exploitation requires local low-privileged execution, unprivileged user and network namespaces, and the ESP-in-TCP path; the public chain overwrites the cached /usr/bin/su image and launches a root shell.

The record

CVE
CVE-2026-46300
Published
May 23, 2026
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-123, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 23, 2026CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=3.9
  2. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c
  3. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <3599e6b3cc1ada96883d496a50a210d3afbb6987
  4. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <3884358a9286b17f389a72b1426fc4547c23c111
  5. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <3bd9e113d50034db99d7ef69fd8e5242d15e414a
  6. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e
  7. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <78bf6b6bb19541d19fbda6242e7cfe2c682763c0
  8. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <9d3e5fd19fe1063bf607219e8562fbd567b8e8d5

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=3.9; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <3599e6b3cc1ada96883d496a50a210d3afbb6987; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <3884358a9286b17f389a72b1426fc4547c23c111; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <3bd9e113d50034db99d7ef69fd8e5242d15e414a; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <78bf6b6bb19541d19fbda6242e7cfe2c682763c0; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <9d3e5fd19fe1063bf607219e8562fbd567b8e8d5

Published CVSS scores

7.8Linux CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8Red HatCVSS: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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-123Write-what-where Condition
T1068Exploitation for Privilege Escalation

Public exploit references

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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