CVE-2024-49768Network attack vector

Request smuggling via lookahead closure race

Published Oct 29, 2024 · Updated Oct 29, 2024

HTTP request smuggling in Pylons Project Waitress 2.0.0 through 3.0.0 allows remote attackers to process a pipelined request. With channel_request_lookahead enabled, HTTPChannel.received accepts a second request after the service thread flags an invalid first request for closure. The nondefault setting and an initial request exactly matching recv_bytes are required; the worker then services a request that the closing connection should discard.

CVSS severity9.3
Critical
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP request smuggling in Pylons Project Waitress 2.0.0 through 3.0.0 allows remote attackers to process a pipelined request. With channel_request_lookahead enabled, HTTPChannel.received accepts a second request after the service thread flags an invalid first request for closure. The nondefault setting and an initial request exactly matching recv_bytes are required; the worker then services a request that the closing connection should discard.

The record

CVE
CVE-2024-49768
Published
Oct 29, 2024
Updated
Oct 29, 2024
Vendor
Pylons Project
Product
Waitress
Classifications
CWE-444, CWE-367, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 29, 2024CVE publishedPublication date reported by the CVE source.
  2. Oct 29, 2024Record 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=>= 2.0.0, < 3.0.1
  2. Affected versionversion=2.0.0 <3.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Pylons Project · Waitressversion=>= 2.0.0, < 3.0.1; version=2.0.0 <3.0.1

Published CVSS scores

9.3GitHubCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

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 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-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
T1190Exploit Public-Facing Application

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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