CVE-2019-16792 [High] | Security Vulnerability in Waitress

Waitress through version 1.3.1 allows request smuggling by sending the Content-Length header twice. Waitress would header fold a double Content-Length header and due to being unable to cast the now comma separated value to an integer would set the Content-Length to 0 internally. If two Content-Length headers are sent in a single request, Waitress would treat the request as having no body, thereby treating the body of the request as a new request in HTTP pipelining. This issue is fixed in Waitress 1.4.0.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2025-11-21	0.64%	0.85%	+0.21%
2	2025-11-18	0.85%	0.64%	-0.21%
3	2025-05-15	—	0.85%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2025-11-21

0.64%

0.85%

+0.21%

2025-11-18

0.85%

0.64%

-0.21%

2025-05-15

—

0.85%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.1	3.1	HIGH	`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/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:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. 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.	1.8	4.7	[email protected]
7.5	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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:N) Doesn’t really leak secrets in a meaningful 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	3.6	[email protected]
5.0	2.0	MEDIUM	`AV:N/AC:L/Au:N/C:N/I:P/A:N` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:N) No availability impact.	10.0	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.1

3.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/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:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
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.

1.8

4.7

[email protected]

7.5

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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:N): Doesn’t really leak secrets in a meaningful 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

3.6

[email protected]

5.0

2.0

MEDIUM

AV:N/AC:L/Au:N/C:N/I:P/A:N Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:N): No availability impact.

10.0

2.9

[email protected]

OS Trackers for CVE-2019-16792

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2019-16792 not yet assigned 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-2019-16792
`suse`	medium	CVE-2019-16792 severity moderate: SUSE including 298 source package names (1.1.1.0.1.5.334:python3-waitress-1.4.3-3.3.1, 1.2.0.0.1.5.338:python3-waitress-1.4.3-3.3.1, …), 542 product×package rows across 38 product lines (Container ses/6/cephcsi/cephcsi, Container ses/6/rook/ceph, … (38 product lines)): Fixed 542.	https://www.suse.com/security/cve/CVE-2019-16792/
`ubuntu`	low	CVE-2019-16792 low priority: Ubuntu including 1 source packages (waitress), 17 status rows across 17 suites (bionic, eoan, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 12, needs-triage 2, DNE 1, ignored 1, released 1.	https://ubuntu.com/security/CVE-2019-16792

Affected software / configurations for CVE-2019-16792

Vendor	Product	Version	Raw CPE
agendaless	waitress	<= 1.3.1	cpe:2.3:a:agendaless:waitress::::::::
oracle	communications_cloud_native_core_network_function_cloud_native_environment	1.10.0	cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment:1.10.0:::::::*
debian	debian_linux	9.0	cpe:2.3:o:debian:debian_linux:9.0:::::::*

References for CVE-2019-16792

URL	Tags
https://docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes	Release Notes
https://github.com/Pylons/waitress/commit/575994cd42e83fd772a5f7ec98b2c56751bd3f65	Patch
https://github.com/Pylons/waitress/security/advisories/GHSA-4ppp-gpcr-7qf6	Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/05/msg00011.html	Mailing List Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.html	Patch Third Party Advisory

URL

CVE-2019-16792 | HTTP Request Smuggling: Content-Length Sent Twice in Waitress

Exploit prediction scoring system (EPSS) score for CVE-2019-16792

Common vulnerability scoring system (CVSS) metrics for CVE-2019-16792

Weakness enumeration for CVE-2019-16792

GitHub Security Advisory for CVE-2019-16792

OS Trackers for CVE-2019-16792

Affected software / configurations for CVE-2019-16792

References for CVE-2019-16792