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NVD / CVE Program· CNA GitHub_M

CVE-2019-16789: HTTP Request Smuggling in Waitress: Invalid whitespace characters in headers

Noroxi assessment

Priority: Monitor (action score 33/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 2.5% (FIRST EPSS); higher than 85.3% of all records.
  • 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.
  • Fixed version: py3-waitress (Alpine:v3.11) 1.4.1-r0; waitress (Debian:12) 1.4.1-1; waitress (Debian:8) 0.8.9-2+deb8u1.

Low priority for now. Upgrade to py3-waitress (Alpine:v3.11) 1.4.1-r0; waitress (Debian:12) 1.4.1-1; waitress (Debian:8) 0.8.9-2+deb8u1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In Waitress through version 1.4.0, if a proxy server is used in front of waitress, an invalid request may be sent by an attacker that bypasses the front-end and is parsed differently by waitress leading to a potential for HTTP request smuggling. Specially crafted requests containing special whitespace characters in the Transfer-Encoding header would get parsed by Waitress as being a chunked request, but a front-end server would use the Content-Length instead as the Transfer-Encoding header is considered invalid due to containing invalid characters. If a front-end server does HTTP pipelining to a backend Waitress server this could lead to HTTP request splitting which may lead to potential cache poisoning or unexpected information disclosure. This issue is fixed in Waitress 1.4.1 through more strict HTTP field validation.

HighCVSS 8.2 · v3.1—No exploit Fix available
Published
Dec 26, 2019
Updated
Jun 16, 2026
EPSS
2.5% · 85th percentile

Report tools

JSON

Action score

33

Monitor

Low priority for now.

CVSS
32 / 40 · 8.2 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.5%

CNA vs NVD score

NVD
8.2
CNA · GitHub_M
7.1
1.1 point gap

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:H/A:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
agendalesswaitress
oraclecommunications cloud native core network function cloud native environment
debiandebian linux
fedoraprojectfedora
redhatopenstack

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • agendaless waitressup to 1.4.0 inclusive
  • debian debian linux9.0
  • fedoraproject fedora30
  • fedoraproject fedora31
  • oracle communications cloud native core network function cloud native environment1.10.0
  • redhat openstack15

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

    • < 1.4.1 and later · before 1.4.1affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.11py3-waitressbefore 1.4.1-r01.4.1-r0
Debian:12waitressbefore 1.4.1-11.4.1-1
Debian:8waitressbefore 0.8.9-2+deb8u10.8.9-2+deb8u1
Debian:9waitressbefore 1.0.1-1+deb9u11.0.1-1+deb9u1
openSUSE:Leap 15.1python-waitressbefore 1.4.3-lp151.3.3.11.4.3-lp151.3.3.1
openSUSE:Leap 15.2python-waitressbefore 1.4.3-lp152.4.3.11.4.3-lp152.4.3.1
PyPIwaitressbefore 1.4.11.4.1
PyPIwaitressbefore 1.4.21.4.2
Red Hat:openstack:15::el8python-waitressbefore 0:1.4.2-1.el8ost0:1.4.2-1.el8ost
Red Hat:openstack:15::el8python3-waitressbefore 0:1.4.2-1.el8ost0:1.4.2-1.el8ost
SUSE:HPE Helion OpenStack 8ansiblebefore 2.4.6.0-3.9.12.4.6.0-3.9.1
SUSE:HPE Helion OpenStack 8ansible1before 1.9.6-7.3.11.9.6-7.3.1
SUSE:HPE Helion OpenStack 8ardana-ansiblebefore 8.0+git.1589740980.6c3bcdc-3.73.18.0+git.1589740980.6c3bcdc-3.73.1
SUSE:HPE Helion OpenStack 8ardana-clusterbefore 8.0+git.1585685203.3e71e49-3.36.18.0+git.1585685203.3e71e49-3.36.1
SUSE:HPE Helion OpenStack 8ardana-freezerbefore 8.0+git.1586539529.b7d295f-3.21.18.0+git.1586539529.b7d295f-3.21.1
SUSE:HPE Helion OpenStack 8ardana-input-modelbefore 8.0+git.1589740934.0e0ad61-3.39.18.0+git.1589740934.0e0ad61-3.39.1
SUSE:HPE Helion OpenStack 8ardana-loggingbefore 8.0+git.1591194866.b7375d0-3.24.18.0+git.1591194866.b7375d0-3.24.1
SUSE:HPE Helion OpenStack 8ardana-mqbefore 8.0+git.1589715269.62ad6df-3.22.18.0+git.1589715269.62ad6df-3.22.1
SUSE:HPE Helion OpenStack 8ardana-neutronbefore 8.0+git.1590756744.ba84abc-3.42.18.0+git.1590756744.ba84abc-3.42.1
SUSE:HPE Helion OpenStack 8ardana-octaviabefore 8.0+git.1590100427.cf4cc8f-3.29.18.0+git.1590100427.cf4cc8f-3.29.1
SUSE:HPE Helion OpenStack 8ardana-osconfigbefore 8.0+git.1587034587.eac37b8-3.45.18.0+git.1587034587.eac37b8-3.45.1
SUSE:HPE Helion OpenStack 8caasp-openstack-heat-templatesbefore 1.0+git.1560518045.ad7dc6d-4.18.11.0+git.1560518045.ad7dc6d-4.18.1
SUSE:HPE Helion OpenStack 8documentation-hpe-helion-openstack-installationbefore 8.20200527-1.26.18.20200527-1.26.1
SUSE:HPE Helion OpenStack 8documentation-hpe-helion-openstack-operationsbefore 8.20200527-1.26.18.20200527-1.26.1

+96

Same product

agendaless: all records

Other highest-scoring records for the same primary product.

  • CVE-2022-24761HTTP Request Smuggling in waitress
    31Monitor
  • CVE-2019-16792HTTP Request Smuggling: Content-Length Sent Twice in Waitress
    31Monitor
  • CVE-2019-16786HTTP Request Smuggling: Invalid Transfer-Encoding in Waitress
    31Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2019-16785Dec 20, 2019 · HTTP Request Smuggling: LF vs CRLF handling in Waitress
    31Monitor
  • Later →CVE-2020-5236Feb 3, 2020 · Catastrophic backtracking in regex allows Denial of Service in Waitress
    27Monitor
  • Later →CVE-2022-31015May 31, 2022 · Uncaught Exception (due to a data race) leads to process termination in Waitress
    23Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:py3-waitress1.4.1-r0 · Alpine:v3.11Package registry (OSV)
debian:waitress1.4.1-1 · Debian:12Package registry (OSV)
opensuse:python-waitress1.4.3-lp152.4.3.1 · openSUSE:Leap 15.2Package registry (OSV)
PyPI:waitress1.4.1Package registry (OSV)
PyPI:waitress1.4.2Package registry (OSV)
red hat:python-waitress0:1.4.2-1.el8ost · Red Hat:openstack:15::el8Package registry (OSV)
red hat:python3-waitress0:1.4.2-1.el8ost · Red Hat:openstack:15::el8Package registry (OSV)
suse:ansible2.2.3.0-12.2 · SUSE:OpenStack Cloud 7Package registry (OSV)
suse:crowbar-core4.0+git.1580209654.1d112d31f-9.66.5 · SUSE:OpenStack Cloud 7Package registry (OSV)
suse:crowbar-ha4.0+git.1585316203.d6ad2c8-4.52.4 · SUSE:OpenStack Cloud 7Package registry (OSV)
suse:crowbar-openstack4.0+git.1589804581.9972163f0-9.71.4 · SUSE:OpenStack Cloud 7Package registry (OSV)
suse:grafana4.6.5-1.14.1 · SUSE:OpenStack Cloud 7Package registry (OSV)
suse:keepalived2.0.19-1.8.1 · SUSE:OpenStack Cloud 7Package registry (OSV)
suse:kibana4.6.3-5.1 · SUSE:OpenStack Cloud 7Package registry (OSV)
suse:memcached1.5.17-3.6.1 · SUSE:OpenStack Cloud 7Package registry (OSV)
suse:monasca-installer20180608_12.47-12.1 · SUSE:OpenStack Cloud 7Package registry (OSV)
suse:openstack-dashboard-theme-SUSE2016.2-5.12.4 · SUSE:OpenStack Cloud 7Package registry (OSV)
suse:openstack-manila3.0.1~dev30-4.12.2 · SUSE:OpenStack Cloud 7Package registry (OSV)
suse:openstack-manila-doc3.0.1~dev30-4.12.3 · SUSE:OpenStack Cloud 7Package 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.

No history yet (it accumulates with the daily EPSS job).

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 researchers

Finders, 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
low · data can be read
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
Low
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:L/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.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records