Uncaught Exception (due to a data race) leads to process termination in Waitress
Impact
Waitress may terminate early due to a thread closing a socket while the main thread is about to call select(). This will lead to the main thread raising an exception that is not handled and then causing the entire application to be killed.
Patches
This issue has been fixed in Waitress 2.1.2 by no longer allowing the WSGI thread to close the socket, instead it is always delegated to the main thread.
Workarounds
There is no work-around, however users using waitress behind a reverse proxy server are less likely to have issues if the reverse proxy always reads the full response.
For more information
If you have any questions or comments about this advisory:
- Open an issue in https://github.com/Pylons/waitress/issues (if not sensitive or security related)
- email the Pylons Security mailing list: pylons-project-security@googlegroups.com (if security related)
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | waitress | >= 2.1.0, < 2.1.2 | 2.1.2 |
References
- https://github.com/Pylons/waitress/pull/377
- https://github.com/Pylons/waitress/issues/374
- https://github.com/Pylons/waitress/security/advisories/GHSA-f5x9-8jwc-25rw
- https://github.com/Pylons/waitress/commit/4f6789b035610e0552738cdc4b35ca809a592d48
- https://nvd.nist.gov/vuln/detail/CVE-2022-31015
- https://github.com/Pylons/waitress
- https://github.com/pypa/advisory-database/tree/main/vulns/waitress/PYSEC-2022-205.yaml
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-248, CWE-362- Platform
- Python (PyPI)
- Package
waitress- Disclosed
- 31.05.2022
- Updated
- 11.10.2026 11:20
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2022-205 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-f5x9-8jwc-25rw - CC BY 4.0
Vulnerability history: waitress
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 10
- First → latest
- 12.2019 10.2024
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
- High 4
- Medium 4
Disclosures per year
- 2019: 5
- 2020: 1
- 2021: 0
- 2022: 2
- 2023: 0
- 2024: 2
- 2025: 0
- 2026: 0
-
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