Description
Waitress is a Web Server Gateway Interface server for Python 2 and 3. A remote client may send a request that is exactly recv_bytes (defaults to 8192) long, followed by a secondary request using HTTP pipelining. When request lookahead is disabled (default) we won't read any more requests, and when the first request fails due to a parsing error, we simply close the connection. However when request lookahead is enabled, it is possible to process and receive the first request, start sending the error message back to the client while we read the next request and queue it. This will allow the secondary request to be serviced by the worker thread while the connection should be closed. Waitress 3.0.1 fixes the race condition. As a workaround, disable channel_request_lookahead, this is set to 0 by default disabling this feature.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Pylons | waitress | >= 2.0.0, < 3.0.1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | waitress | 3.0.1-1 | — |
| Debian 13 | waitress | 3.0.1-1 | — |
| Debian 12 | waitress | 2.1.2-2+deb12u1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | waitress | 1.4.4-1.1ubuntu1.1 | USN-7115-1 |
| Ubuntu 20.04 LTS | waitress | 1.4.1-1ubuntu0.2 | USN-7115-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 24.04 LTS | waitress | 2.1.2-2ubuntu0.1~esm1 | USN-7115-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Openshift Ironic 4 | python-waitress +1 | 3.0.1-1.el9 | RHSA-2024:10815, RHSA-2024:10535, RHSA-2024:10145 |
| Red Hat OpenStack 17 | python-waitress +1 | 2.0.0-4.el8ost | RHSA-2025:1192, RHSA-2025:1191 |
| Red Hat OpenStack 16 | python-waitress +1 | 2.0.0-4.el8ost | RHSA-2025:0201 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP4 | python-waitress +1 | 2.1.2-150400.12.7.1 | SUSE-SU-2024:3876-1 |
| SLES 3 | python-waitress +1 | 2.1.2-150400.12.7.1 | SUSE-SU-2024:3876-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLE HPC 15 SP4 | python-waitress +1 | 2.1.2-150400.12.7.1 | SUSE-SU-2024:3876-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.5 | python-waitress +1 | 2.1.2-150400.12.7.1 | SUSE-SU-2024:3876-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | python3-waitress | 2.1.2-1.amzn2023.0.3 | ALAS2023-2024-773 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | python-waitress | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | waitress | >= 2.0.0, < 3.0.1 | 3.0.1 | GHSA-9298-4cf8-g4wj |
Advisories 13
- WID-SEC-2024-3488 Red Hat OpenShift Container Platform: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 18, 2026
- RHSA-2025:1192 Red Hat Security Advisory: Red Hat OpenStack Platform 17.1 (python-waitress) security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- RHSA-2025:1191 Red Hat Security Advisory: Red Hat OpenStack Platform 17.1 (python-waitress) security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- RHSA-2025:0201 Red Hat Security Advisory: Red Hat OpenStack Platform 16.2 (python-waitress) security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- RHSA-2024:9623 Red Hat Security Advisory: OpenShift Container Platform 4.14.41 packages and security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- RHSA-2024:9618 Red Hat Security Advisory: OpenShift Container Platform 4.16.23 packages and security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- RHSA-2024:9613 Red Hat Security Advisory: OpenShift Container Platform 4.17.5 security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- RHSA-2024:10815 Red Hat Security Advisory: OpenShift Container Platform 4.13.54 packages and security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- RHSA-2024:10535 Red Hat Security Advisory: OpenShift Container Platform 4.12.70 security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- RHSA-2024:10145 Red Hat Security Advisory: OpenShift Container Platform 4.15.39 packages and security update Red Hat Security Advisories (RHSA) · Jul 3, 2026
- USN-7115-1 Waitress vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- SUSE-SU-2024:3876-1 Security update for python-waitress SUSE / openSUSE Security Updates · Feb 4, 2026
- ALAS2023-2024-773 Important: python-waitress security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Dec 16, 2024