CVE-2026-52946Network attack vector

Remote system hang via fasync lock deadlock

Published Jun 24, 2026 · Updated Jun 24, 2026

Deadlock in affected Linux Kernel releases allows remote attackers to hang exposed systems through crafted TCP URG traffic. The send_sigio() and send_sigurg() process-group paths take tasklist_lock for reading from softirq context, where writer fairness can block the nested reader and deadlock the kernel. Reachability requires a network service whose socket owner uses FASYNC process-group signaling while concurrent fork, exit, or wait activity exercises a tasklist_lock writer or reader.

CVSS severity7.5
High
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deadlock in affected Linux Kernel releases allows remote attackers to hang exposed systems through crafted TCP URG traffic. The send_sigio() and send_sigurg() process-group paths take tasklist_lock for reading from softirq context, where writer fairness can block the nested reader and deadlock the kernel. Reachability requires a network service whose socket owner uses FASYNC process-group signaling while concurrent fork, exit, or wait activity exercises a tasklist_lock writer or reader.

The record

CVE
CVE-2026-52946
Published
Jun 24, 2026
Updated
Jun 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-667, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 24, 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=0 <5.10.259
  2. Affected versionversion=0 <5.15.210
  3. Affected versionversion=0 <6.1.176
  4. Affected versionversion=0 <6.12.94
  5. Affected versionversion=0 <6.18.36
  6. Affected versionversion=0 <6.6.143
  7. Affected versionversion=0 <7.0.13
  8. Affected versionversion=0 <7.1.1
  9. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1bee417678f1135e35b25a37734db46aa94258d2
  10. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <20a93e397abe850c49b6fa0e8cc827b5f634a8f5
  11. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <32dbd5ce4be3a3ed7e00f8af18795cc84fc50a33
  12. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <36c1b57b2ecf3c61ac93f5f07bd29b6f21e226ed
  13. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <54626335ea4174ab2d9a183b511d825f6765e47b
  14. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <897d6a7247739fb1528f98c575df4f2e5de7f994
  15. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b5fa9e32fb6718f70c986ee14dd5d01b4846f331
  16. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bfcc8e8d8a495bb34cae9e620adfb75fb13a3954

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0 <5.10.259; version=0 <5.15.210; version=0 <6.1.176; version=0 <6.12.94; version=0 <6.18.36; version=0 <6.6.143; version=0 <7.0.13; version=0 <7.1.1; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1bee417678f1135e35b25a37734db46aa94258d2; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <20a93e397abe850c49b6fa0e8cc827b5f634a8f5; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <32dbd5ce4be3a3ed7e00f8af18795cc84fc50a33; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <36c1b57b2ecf3c61ac93f5f07bd29b6f21e226ed; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <54626335ea4174ab2d9a183b511d825f6765e47b; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <897d6a7247739fb1528f98c575df4f2e5de7f994; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b5fa9e32fb6718f70c986ee14dd5d01b4846f331; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bfcc8e8d8a495bb34cae9e620adfb75fb13a3954

Published CVSS scores

7.5LinuxCVSS:3.1/AV:N/AC:L/PR:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-667Improper Locking
T1499.004Application or System Exploitation

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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