HTTP Request Smuggling: Content-Length Sent Twice 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.
- Published
- Jan 22, 2020
- Updated
- Jun 16, 2026
- EPSS
- 2.0% · 80th percentile
- CWE
- CWE-444
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Report tools
Action score
31
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.0%
CNA vs NVD score
- NVD
- 7.5
- CNA · GitHub_M
- 7.1
- 0.4 point gap
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| agendaless | waitress | cpe:2.3:a:agendaless:waitress |
| oracle | communications cloud native core network function cloud native environment | cpe:2.3:a:oracle:communications_cloud_native_core_network_function_cloud_native_environment |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- agendaless waitressup to 1.3.1 inclusive
- debian debian linux9.0
- oracle communications cloud native core network function cloud native environment1.10.0
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
Pylons Waitress
- <= 1.3.1 and later · up to and including 1.3.1affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | waitress | before 1.4.1-1 | 1.4.1-1 |
| Debian:9 | waitress | before 1.0.1-1+deb9u1 | 1.0.1-1+deb9u1 |
| openSUSE:Leap 15.1 | python-waitress | before 1.4.3-lp151.3.3.1 | 1.4.3-lp151.3.3.1 |
| openSUSE:Leap 15.2 | python-waitress | before 1.4.3-lp152.4.3.1 | 1.4.3-lp152.4.3.1 |
| PyPI | waitress | before 1.4.0 | 1.4.0 |
| SUSE:HPE Helion OpenStack 8 | ansible | before 2.4.6.0-3.9.1 | 2.4.6.0-3.9.1 |
| SUSE:HPE Helion OpenStack 8 | ansible1 | before 1.9.6-7.3.1 | 1.9.6-7.3.1 |
| SUSE:HPE Helion OpenStack 8 | ardana-ansible | before 8.0+git.1589740980.6c3bcdc-3.73.1 | 8.0+git.1589740980.6c3bcdc-3.73.1 |
| SUSE:HPE Helion OpenStack 8 | ardana-cluster | before 8.0+git.1585685203.3e71e49-3.36.1 | 8.0+git.1585685203.3e71e49-3.36.1 |
| SUSE:HPE Helion OpenStack 8 | ardana-freezer | before 8.0+git.1586539529.b7d295f-3.21.1 | 8.0+git.1586539529.b7d295f-3.21.1 |
| SUSE:HPE Helion OpenStack 8 | ardana-input-model | before 8.0+git.1589740934.0e0ad61-3.39.1 | 8.0+git.1589740934.0e0ad61-3.39.1 |
| SUSE:HPE Helion OpenStack 8 | ardana-logging | before 8.0+git.1591194866.b7375d0-3.24.1 | 8.0+git.1591194866.b7375d0-3.24.1 |
| SUSE:HPE Helion OpenStack 8 | ardana-mq | before 8.0+git.1589715269.62ad6df-3.22.1 | 8.0+git.1589715269.62ad6df-3.22.1 |
| SUSE:HPE Helion OpenStack 8 | ardana-neutron | before 8.0+git.1590756744.ba84abc-3.42.1 | 8.0+git.1590756744.ba84abc-3.42.1 |
| SUSE:HPE Helion OpenStack 8 | ardana-octavia | before 8.0+git.1590100427.cf4cc8f-3.29.1 | 8.0+git.1590100427.cf4cc8f-3.29.1 |
| SUSE:HPE Helion OpenStack 8 | ardana-osconfig | before 8.0+git.1587034587.eac37b8-3.45.1 | 8.0+git.1587034587.eac37b8-3.45.1 |
| SUSE:HPE Helion OpenStack 8 | caasp-openstack-heat-templates | before 1.0+git.1560518045.ad7dc6d-4.18.1 | 1.0+git.1560518045.ad7dc6d-4.18.1 |
| SUSE:HPE Helion OpenStack 8 | documentation-hpe-helion-openstack-installation | before 8.20200527-1.26.1 | 8.20200527-1.26.1 |
| SUSE:HPE Helion OpenStack 8 | documentation-hpe-helion-openstack-operations | before 8.20200527-1.26.1 | 8.20200527-1.26.1 |
| SUSE:HPE Helion OpenStack 8 | documentation-hpe-helion-openstack-opsconsole | before 8.20200527-1.26.1 | 8.20200527-1.26.1 |
| SUSE:HPE Helion OpenStack 8 | documentation-hpe-helion-openstack-planning | before 8.20200527-1.26.1 | 8.20200527-1.26.1 |
| SUSE:HPE Helion OpenStack 8 | documentation-hpe-helion-openstack-security | before 8.20200527-1.26.1 | 8.20200527-1.26.1 |
| SUSE:HPE Helion OpenStack 8 | documentation-hpe-helion-openstack-user | before 8.20200527-1.26.1 | 8.20200527-1.26.1 |
| SUSE:HPE Helion OpenStack 8 | grafana | before 4.6.5-4.9.1 | 4.6.5-4.9.1 |
+96
Same product
agendaless: all recordsOther highest-scoring records for the same primary product.
- CVE-2019-16789HTTP Request Smuggling in Waitress: Invalid whitespace characters in headers33Monitor
- CVE-2022-24761HTTP Request Smuggling in waitress31Monitor
- CVE-2019-16786HTTP Request Smuggling: Invalid Transfer-Encoding in Waitress31Monitor
- CVE-2019-16785HTTP Request Smuggling: LF vs CRLF handling in Waitress31Monitor
- CVE-2024-49769Waitress has a denial of service leading to high CPU usage/resource exhaustion30Monitor
- CVE-2020-5236Catastrophic backtracking in regex allows Denial of Service in Waitress27Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:waitress | 1.4.1-1 · Debian:12 | Package registry (OSV) |
| opensuse:python-waitress | 1.4.3-lp152.4.3.1 · openSUSE:Leap 15.2 | Package registry (OSV) |
| PyPI:waitress | 1.4.0 | Package registry (OSV) |
| suse:ansible | 2.2.3.0-12.2 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:crowbar-core | 4.0+git.1580209654.1d112d31f-9.66.5 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:crowbar-ha | 4.0+git.1585316203.d6ad2c8-4.52.4 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:crowbar-openstack | 4.0+git.1589804581.9972163f0-9.71.4 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:grafana | 4.6.5-1.14.1 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:keepalived | 2.0.19-1.8.1 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:kibana | 4.6.3-5.1 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:memcached | 1.5.17-3.6.1 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:monasca-installer | 20180608_12.47-12.1 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:openstack-dashboard-theme-SUSE | 2016.2-5.12.4 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:openstack-manila | 3.0.1~dev30-4.12.2 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
| suse:openstack-manila-doc | 3.0.1~dev30-4.12.3 · SUSE:OpenStack Cloud 7 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- high · data or configuration can be modified
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- High
- Availability impact
- None
Weakness class (CWE)
CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes
- github.com/Pylons/waitress/commit/575994cd42e83fd772a5f7ec98b2c56751bd3f65
- github.com/Pylons/waitress/security/advisories/GHSA-4ppp-gpcr-7qf6
- lists.debian.org/debian-lts-announce/2022/05/msg00011.html
- www.oracle.com/security-alerts/cpuapr2022.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.