CVE-2026-43503Public exploit

Local root escalation via lost shared-frag marker

Published May 23, 2026 · Updated May 23, 2026

Memory corruption in the Linux Kernel allows local users to gain root access through crafted socket-buffer fragment transfers. Fragment-transfer helpers move page-backed frags without preserving SKBFL_SHARED_FRAG, so ESP decryption skips copy-on-write and overwrites a root-owned file page in cache. Exploitation requires local access and CAP_NET_ADMIN, obtainable through enabled unprivileged user namespaces; the bounded result is page-cache modification and root execution.

CVSS severity8.8
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in the Linux Kernel allows local users to gain root access through crafted socket-buffer fragment transfers. Fragment-transfer helpers move page-backed frags without preserving SKBFL_SHARED_FRAG, so ESP decryption skips copy-on-write and overwrites a root-owned file page in cache. Exploitation requires local access and CAP_NET_ADMIN, obtainable through enabled unprivileged user namespaces; the bounded result is page-cache modification and root execution.

The record

CVE
CVE-2026-43503
Published
May 23, 2026
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-664, 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 <12401fcfb01f53ccc63ab0a3246570fe8f3105ee
  3. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <179f1852bdedc300e373e807cc102cd81feff196
  4. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <989214c66884d70716d83dc1d0bf5e16287bf349
  5. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <9bc9d6d6967a2239aa57af2aa53554eddd640d20
  6. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <fbeab9555564a1b98e8582cd106dfe46c4606991
  7. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <fc6eb39c55e97df2f94ad974b8a5bbcd019da2c8
  8. Affected versionversion=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <ff375cc75f9167168db38e0464a482d5fbc8d81d

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=3.9; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <12401fcfb01f53ccc63ab0a3246570fe8f3105ee; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <179f1852bdedc300e373e807cc102cd81feff196; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <989214c66884d70716d83dc1d0bf5e16287bf349; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <9bc9d6d6967a2239aa57af2aa53554eddd640d20; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <fbeab9555564a1b98e8582cd106dfe46c4606991; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <fc6eb39c55e97df2f94ad974b8a5bbcd019da2c8; version=cef401de7be8c4e155c6746bfccf721a4fa5fab9 <ff375cc75f9167168db38e0464a482d5fbc8d81d

Published CVSS scores

8.8kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
7.0redhat-SADPCVSS: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 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-664Improper Control of a Resource Through its Lifetime
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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