CVE-2022-49561

Host crash via stale conntrack pointer reuse

Published Feb 26, 2025 · Updated Aug 5, 2026

Use-after-free in Linux kernel netfilter conntrack allows local users to crash the host through a connection-insertion race. nf_conntrack_confirm() fails to reload skb->_nfct after __nf_conntrack_confirm() can free and replace the clashing entry, so cached-event delivery uses stale state. Exploitation requires conntrack events to be enabled and a controllable insertion clash; the grounded consequence is a kernel crash and service interruption.

CVSS severity5.5
Medium
EPSS probability0.82%
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 netfilter conntrack allows local users to crash the host through a connection-insertion race. nf_conntrack_confirm() fails to reload skb->_nfct after __nf_conntrack_confirm() can free and replace the clashing entry, so cached-event delivery uses stale state. Exploitation requires conntrack events to be enabled and a controllable insertion clash; the grounded consequence is a kernel crash and service interruption.

The record

CVE
CVE-2022-49561
Published
Feb 26, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 26, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=4.7
  2. Affected versionversion=71d8c47fc653711c41bc3282e5b0e605b3727956 <01989d7eebb61c99bd4b88ebc8e261bd2f02caed
  3. Affected versionversion=71d8c47fc653711c41bc3282e5b0e605b3727956 <04e4a11dc723c52db7a36dc58f0d69ce6426f8f0
  4. Affected versionversion=71d8c47fc653711c41bc3282e5b0e605b3727956 <04f9e9104c969d8ce10a4a43634f641ed082092d
  5. Affected versionversion=71d8c47fc653711c41bc3282e5b0e605b3727956 <56b14ecec97f39118bf85c9ac2438c5a949509ed
  6. Affected versionversion=71d8c47fc653711c41bc3282e5b0e605b3727956 <91a36ec160ec1a0c8f5352b772dffcbb0b6023e3
  7. Affected versionversion=71d8c47fc653711c41bc3282e5b0e605b3727956 <92a999d1963eed0df666284e20055136ceabd12f
  8. Affected versionversion=71d8c47fc653711c41bc3282e5b0e605b3727956 <b16bb373988da3ceb0308381634117e18b6ec60d
  9. Affected versionversion=71d8c47fc653711c41bc3282e5b0e605b3727956 <e97222b785e70e8973281666d709baad6523d8af

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.7; version=71d8c47fc653711c41bc3282e5b0e605b3727956 <01989d7eebb61c99bd4b88ebc8e261bd2f02caed; version=71d8c47fc653711c41bc3282e5b0e605b3727956 <04e4a11dc723c52db7a36dc58f0d69ce6426f8f0; version=71d8c47fc653711c41bc3282e5b0e605b3727956 <04f9e9104c969d8ce10a4a43634f641ed082092d; version=71d8c47fc653711c41bc3282e5b0e605b3727956 <56b14ecec97f39118bf85c9ac2438c5a949509ed; version=71d8c47fc653711c41bc3282e5b0e605b3727956 <91a36ec160ec1a0c8f5352b772dffcbb0b6023e3; version=71d8c47fc653711c41bc3282e5b0e605b3727956 <92a999d1963eed0df666284e20055136ceabd12f; version=71d8c47fc653711c41bc3282e5b0e605b3727956 <b16bb373988da3ceb0308381634117e18b6ec60d; version=71d8c47fc653711c41bc3282e5b0e605b3727956 <e97222b785e70e8973281666d709baad6523d8af

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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

T1499Endpoint Denial of Service

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

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Your stack

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