HTTP Request Smuggling in Waitress: Invalid whitespace characters in headers (Follow-up)GHSA-968f-66r5-5v74
HIGHFix: github/advisory-review#14604GHSA-968f-66r5-5v74 is a high-severity (CVSS 7.1) CWE-444 vulnerability in waitress. A fix is available for waitress — see the affected versions and patch details below.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
waitressReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Impact
The patches introduced to fix https://github.com/Pylons/waitress/security/advisories/GHSA-m5ff-3wj3-8ph4 were not complete and still would allow an attacker to smuggle requests/split a HTTP request with invalid data.
This updates the existing CVE with ID: CVE-2019-16789
Patches
Waitress version 1.4.2 has been updated to now validate HTTP headers better to avoid the issue, completely fixing all known issues with whitespace.
Workarounds
There are no work-arounds, upgrading to Waitress 1.4.2 is highly recommended.
References
See https://github.com/Pylons/waitress/security/advisories/GHSA-m5ff-3wj3-8ph4 for more information on the security issue.
For more information
If you have any questions or comments about this advisory:
- open an issue at https://github.com/Pylons/waitress/issues (if not sensitive or security related)
- email the Pylons Security mailing list: [email protected] (if security related)
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | waitress | all versions | 1.4.2pip install --upgrade 'waitress==1.4.2' |
Affected Products
waitressagendalessdebian linuxdebianfedorafedoraprojectcommunications cloud native core network function cloud native environmentoracleopenstackredhatDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for waitress, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update waitress to 1.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-968f-66r5-5v74 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
All affected Red Hat products ship but do not use the flawed version of python-waitress. The impact for these products is therefore rated as having a security impact of Low. For Red Hat OpenStack Platform 13, because the flaw has a lower impact and the fix would require a substantial amount of development, no update…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat OpenStack Platform 15.0 (Stein) | python-waitress-0:1.4.2-1.el8ost | RHSA-2020:0720 |
| Red Hat Quay 3 | quay/clair-rhel8:v3.4.0-25 | RHSA-2021:0420 |
Frequently Asked Questions
Is GHSA-968f-66r5-5v74 in your dependencies?
Find it across PyPI, including transitive dependencies.