CVE-2022-31015Public exploitNetwork attack vector

Server termination via worker-thread socket-close race

Published May 31, 2022 · Updated Apr 22, 2025

Denial of service in Pylons Project Waitress 2.1.0 through 2.1.1 allows remote attackers to terminate the server via a client disconnect. A WSGI worker can close the client's socket while the main thread enters select(), causing an uncaught exception in the main loop. Triggering the race requires a disconnect during response transmission; a reverse proxy that fully reads responses reduces exposure.

CVSS severity5.9
Medium
EPSS probability1.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Pylons Project Waitress 2.1.0 through 2.1.1 allows remote attackers to terminate the server via a client disconnect. A WSGI worker can close the client's socket while the main thread enters select(), causing an uncaught exception in the main loop. Triggering the race requires a disconnect during response transmission; a reverse proxy that fully reads responses reduces exposure.

The record

CVE
CVE-2022-31015
Published
May 31, 2022
Updated
Apr 22, 2025
Vendor
Pylons Project
Product
Waitress
Classifications
CWE-248, CWE-362, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 31, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2025Record 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=>= 2.1.0, < 2.1.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Pylons Project · Waitressversion=>= 2.1.0, < 2.1.2

Published CVSS scores

6.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
5.9NIST NVDCVSS:3.1/AV:N/AC:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-248Uncaught Exception
CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1499.004Application or System Exploitation

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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