CVE-2023-27522: HTTP Response Smuggling vulnerability in Apache HTTP Server via mod_proxy_uwsgi

Q: How do I fix CVE-2023-27522?

http server: upgrade to 2.4.56; debian linux: mitigate or apply the listed mitigation; uwsgi: upgrade to 2.0.22. Exact commands for each OS are on this page.

Q: Is CVE-2023-27522 being exploited?

CVE-2023-27522 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2023-27522 affect?

CVE-2023-27522 affects http server, debian linux, uwsgi. Severity is high (CVSS 7.5). 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. Special characters in the origin response header can truncate/split the response forwarded

Q: How urgent is CVE-2023-27522?

Priority 57/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

This month

HIGH 7.5REMOTEWATCHLISTUPGRADEMITIGATEUPGRADE

CVE-2023-27522 is a high-severity flaw (CVSS 7.5) affecting http server, debian linux, uwsgi. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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. Special characters in the origin response header can truncate/split the response forwarded to the client.

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.1% (top 18%)
CISA exploited list	No
Weakness	CWE-444
Published	2023-03-07
Last modified	2026-06-17

Publisher (CNA): Apache Software Foundation · Vendor: apache · debian · unbit

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-03-07 16:15 UTCPublished CVE record published
2026-06-17 05:45 UTCUpdated Record last modified

apache http server UPGRADE

Affected: >= 2.4.30 and < 2.4.56

Fixed in: 2.4.56

Safe to downgrade to: a release before 2.4.30

1. Check installed version

apt-cache policy http-server || rpm -q http-server || http-server --version

2. UPGRADE to 2.4.56 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade http-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade http-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.4.30 (Debian / Ubuntu)

apt-cache madison http-server sudo apt install http-server=<VERSION_BEFORE_2.4.30> sudo apt-mark hold http-server

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list http-server sudo dnf downgrade http-server-<VERSION_BEFORE_2.4.30> sudo dnf versionlock add http-server

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

debian debian linux MITIGATE

Affected: 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

unbit uwsgi UPGRADE

Affected: < 2.0.22

Fixed in: 2.0.22

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy uwsgi || rpm -q uwsgi || uwsgi --version

2. UPGRADE to 2.0.22 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade uwsgi

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade uwsgi

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-27522?

http server: upgrade to 2.4.56; debian linux: mitigate or apply the listed mitigation; uwsgi: upgrade to 2.0.22. Exact commands for each OS are on this page.

Is CVE-2023-27522 being exploited?

CVE-2023-27522 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-27522 affect?

CVE-2023-27522 affects http server, debian linux, uwsgi. Severity is high (CVSS 7.5). 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. Special characters in the origin response header can truncate/split the response forwarded

How urgent is CVE-2023-27522?

Priority 57/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Apache HTTP Server vulnerabilities · Debian vulnerabilities

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References

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