CVE-2024-49768 | Waitress has request processing race condition in HTTP pipelining with invalid first request

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.

Published: 2024-10-29 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2024-49768 is rated Moderate Risk (49.7/100): CVSS Critical severity, with low exploitation likelihood (EPSS 0.49%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2024-49768

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.57% 0.49% -0.08%
2 2026-05-25 0.52% 0.57% +0.06%
3 2026-05-12 — 0.52% —

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2024-49768

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.1 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 5.2 [email protected]
4.8 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 2.5 [email protected]

Weakness enumeration for CVE-2024-49768

GitHub Security Advisory for CVE-2024-49768

GHSA-9298-4cf8-g4wj · Severity: critical · Ecosystem: pip — Waitress has request processing race condition in HTTP pipelining with invalid first request

OS Trackers for CVE-2024-49768

vendor priority summary link
debian unimportant CVE-2024-49768 unimportant priority: Debian including 1 source packages (waitress), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2024-49768
redhat high — https://access.redhat.com/security/cve/CVE-2024-49768
suse high CVE-2024-49768 severity important: SUSE including 8 source package names (python-waitress, python2-waitress, …), 55 product×package rows across 27 product lines (SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS, SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS, … (27 product lines)): Known Not Affected 35, Fixed 20. https://www.suse.com/security/cve/CVE-2024-49768/
ubuntu medium CVE-2024-49768 medium priority: Ubuntu including 1 source packages (waitress), 9 status rows across 9 suites (bionic, focal, jammy, noble, oracular, plucky, questing, upstream, xenial): not-affected 6, released 3. https://ubuntu.com/security/CVE-2024-49768

Affected software / configurations for CVE-2024-49768

Vendor Product Version Raw CPE
agendaless waitress >= 2.0.0, < 3.0.1 cpe:2.3:a:agendaless:waitress:*:*:*:*:*:*:*:*

References for CVE-2024-49768

cvelogic Threat Intelligence