CVE-2023-27522 is a high-severity (CVSS 7.5) CWE-444 vulnerability in uwsgi. A fix is available for uwsgi — see the affected versions and patch details below.
Apache HTTP Server: mod_proxy_uwsgi HTTP response splitting
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-27522.
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
uwsgiReal-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
HTTP Response Smuggling vulnerability in Apache HTTP Server via mod_proxy_uwsgi. This issue affects Apache HTTP Server from 2.4.30 through 2.4.55 and the uWSGI PyPI package prior to version 2.0.22. Special characters in the origin response header can truncate/split the response forwarded to the client.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | uwsgi | all versions | 2.0.22pip install --upgrade 'uwsgi==2.0.22' |
Affected Products
http serverapachedebian linuxdebianuwsgiunbitDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for uwsgi, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update uwsgi to 2.0.22 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-27522 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.
The HTTP Response Smuggling vulnerability in Apache HTTP Server via mod_proxy_uwsgi has been categorized as moderate severity for Red Hat Enterprise Linux due to several technical factors. While the potential impact of this vulnerability is significant, its exploitation requires specific conditions, including the…
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.Source: Red Hat security advisory for CVE-2023-27522 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| JBoss Core Services for RHEL 8 | jbcs-httpd24-httpd-0:2.4.57-5.el8jbcs | RHSA-2023:4629 |
| Red Hat Enterprise Linux 8 | httpd:2.4-8080020230830144124.63b34585 | RHSA-2023:5050 |
| Red Hat Enterprise Linux 8.6 Extended Update Support | httpd:2.4-8060020230830144749.ad008a3a | RHSA-2023:5049 |
| Red Hat Enterprise Linux 9 | httpd-0:2.4.57-5.el9 | RHSA-2023:6403 |
| Red Hat Enterprise Linux 9.2 Extended Update Support | httpd-0:2.4.53-11.el9_2.6 | RHSA-2024:4504 |
| Red Hat JBoss Core Services 2.4.57 | httpd | RHSA-2023:4628 |
Frequently Asked Questions
Is CVE-2023-27522 in your dependencies?
Find it across PyPI, including transitive dependencies.