CVE-2024-49768

Waitress has request processing race condition in HTTP pipelining with invalid first request

Severity Score

9.1

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

Attend

*SSVC

Descriptions

NVD
RedHat

Waitress is a Web Server Gateway Interface server for Python 2 and 3. A remote client may send a request that is exactly recv_bytes (defaults to 8192) long, followed by a secondary request using HTTP pipelining. When request lookahead is disabled (default) we won't read any more requests, and when the first request fails due to a parsing error, we simply close the connection. However when request lookahead is enabled, it is possible to process and receive the first request, start sending the error message back to the client while we read the next request and queue it. This will allow the secondary request to be serviced by the worker thread while the connection should be closed. Waitress 3.0.1 fixes the race condition. As a workaround, disable channel_request_lookahead, this is set to 0 by default disabling this feature.

A flaw was found in the Waitress WSGI server for Python. A remote client can send a request that is exactly `recv_bytes`, which defaults to 8192 long, followed by a secondary request using HTTP pipelining. When request lookahead is disabled (default), Waitress won't read any more requests, and when the first request fails due to a parsing error, it simply closes the connection.

However when request lookahead is enabled, it is possible to process and receive the first request, start sending the error message back to the client while we read the next request and queue it. This will allow the secondary request to be serviced by the worker thread while the connection should be closed.

*Credits: N/A

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:Attend

Exploitation

None

Automatable

Yes

Tech. Impact

Total

* Organization's Worst-case Scenario

Timeline

2024-10-18 CVE Reserved
2024-10-29 CVE Published
2024-10-29 CVE Updated
2024-11-08 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

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

CAPEC

References (4)

URL	Tag	Source
https://github.com/Pylons/waitress/commit/e4359018537af376cf24bd13616d861e2fb76f65	X_refsource_misc
https://github.com/Pylons/waitress/security/advisories/GHSA-9298-4cf8-g4wj	X_refsource_confirm

URL	Date	SRC

URL	Date	SRC

URL	Date	SRC
https://access.redhat.com/security/cve/CVE-2024-49768	2024-11-20
https://bugzilla.redhat.com/show_bug.cgi?id=2322460	2024-11-20

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Pylons Search vendor "Pylons"		Waitress Search vendor "Pylons" for product "Waitress"				>= 2.0.0 < 3.0.1 Search vendor "Pylons" for product "Waitress" and version " >= 2.0.0 < 3.0.1"		en		Affected