CVE-2026-43027

Kernel use-after-free via stale helper expectations

Published May 1, 2026 · Updated May 1, 2026

Use-after-free in Linux Kernel allows local users to trigger freed-memory dereferences through stale netfilter helper expectations. nf_conntrack_helper_unregister() passes NULL instead of the helper to expectation cleanup, leaving exp->helper references alive after nfnl_cthelper_del() frees the helper. The path requires local low-privileged access; expectation dumps or packet-driven connection tracking trigger the stale pointer, while upstream does not establish a specific end impact.

CVSS severity7.8
High
EPSS probability0.13%
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 Linux Kernel allows local users to trigger freed-memory dereferences through stale netfilter helper expectations. nf_conntrack_helper_unregister() passes NULL instead of the helper to expectation cleanup, leaving exp->helper references alive after nfnl_cthelper_del() frees the helper. The path requires local low-privileged access; expectation dumps or packet-driven connection tracking trigger the stale pointer, while upstream does not establish a specific end impact.

The record

CVE
CVE-2026-43027
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 1, 2026CVE publishedPublication date reported by the CVE source.
  2. May 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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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=ac7b848390036dadd4351899d2a23748075916bd <2c16e4d64dd91227742dfe196a3e7b0568bef65a
  3. Affected versionversion=ac7b848390036dadd4351899d2a23748075916bd <2cf2737c85a2ba2b52024dafe68ffad2676f97be
  4. Affected versionversion=ac7b848390036dadd4351899d2a23748075916bd <504ba4168466c91210c45acdc332479cfd5f2da6
  5. Affected versionversion=ac7b848390036dadd4351899d2a23748075916bd <5cf28d5c8dcbbe8af6d3b145babe491906d7bad1
  6. Affected versionversion=ac7b848390036dadd4351899d2a23748075916bd <620f3d14c1ef51d425060a3056ad8dbae8f998a3
  7. Affected versionversion=ac7b848390036dadd4351899d2a23748075916bd <90bd7e8501349db3006d21fbc09df9ffcb172965
  8. Affected versionversion=ac7b848390036dadd4351899d2a23748075916bd <a242a9ae58aa46ff7dae51ce64150a93957abe65
  9. Affected versionversion=ac7b848390036dadd4351899d2a23748075916bd <dc1739eff48e34cc71d4e2f03715493fbcebd8af

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=4.14; version=ac7b848390036dadd4351899d2a23748075916bd <2c16e4d64dd91227742dfe196a3e7b0568bef65a; version=ac7b848390036dadd4351899d2a23748075916bd <2cf2737c85a2ba2b52024dafe68ffad2676f97be; version=ac7b848390036dadd4351899d2a23748075916bd <504ba4168466c91210c45acdc332479cfd5f2da6; version=ac7b848390036dadd4351899d2a23748075916bd <5cf28d5c8dcbbe8af6d3b145babe491906d7bad1; version=ac7b848390036dadd4351899d2a23748075916bd <620f3d14c1ef51d425060a3056ad8dbae8f998a3; version=ac7b848390036dadd4351899d2a23748075916bd <90bd7e8501349db3006d21fbc09df9ffcb172965; version=ac7b848390036dadd4351899d2a23748075916bd <a242a9ae58aa46ff7dae51ce64150a93957abe65; version=ac7b848390036dadd4351899d2a23748075916bd <dc1739eff48e34cc71d4e2f03715493fbcebd8af

Published CVSS scores

7.8NIST National Vulnerability DatabaseCVSS: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 exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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