Skip to content
Noroxi
NVD / CVE Program· CNA apache

CVE-2023-27522: Apache HTTP Server: mod_proxy_uwsgi HTTP response splitting

HighCVSS 7.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 2.1% (FIRST EPSS); higher than 82.2% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: httpd (AlmaLinux:8) 2.4.37-56.module_el8.8.0+3605+a3cf1030.7; httpd-devel (AlmaLinux:8) 2.4.37-56.module_el8.8.0+3605+a3cf1030.7; httpd-filesystem (AlmaLinux:8) 2.4.37-56.module_el8.8.0+3605+a3cf1030.7.
  • Mentioned 3 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to httpd (AlmaLinux:8) 2.4.37-56.module_el8.8.0+3605+a3cf1030.7; httpd-devel (AlmaLinux:8) 2.4.37-56.module_el8.8.0+3605+a3cf1030.7; httpd-filesystem (AlmaLinux:8) 2.4.37-56.module_el8.8.0+3605+a3cf1030.7 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

Published
Mar 7, 2023
Updated
Jun 17, 2026
EPSS
2.1% · 82th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.1%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2023-27522

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits every 10 minutes on paid plans, on the hour on the free plan.

Is Apache HTTP Server on your server exposed to the internet?Run a port scan

Your free account also gets you

  • CVE alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools, at most 30 a day (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for apache records

Is Apache HTTP Server on your server exposed to the internet?Run a port scan

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
apachehttp server
debiandebian linux
unbituwsgi

Using http server? Add it to your stack and be the first to know about CVEs like this one. (Apache HTTP)

Watch new CVEs for http server

When you'll hear from us

  • when a new CVE affecting this product is published
  • when a record in your stack enters KEV or is weaponized

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits every 10 minutes on paid plans, on the hour on the free plan.

Is Apache HTTP Server on your server exposed to the internet?Run a port scan

Your free account also gets you

  • CVE alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools, at most 30 a day (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every Monday

Is Apache HTTP Server on your server exposed to the internet?

The free port scanner finds the open ports on your server and matches the service versions it can read against known vulnerabilities. No account needed.

Run a port scan

Versions reported by the vendor

Affected version ranges reported by the assigning authority (apache). Independent of NVD's CPE analysis and usually ahead of it.

  • Apache Software Foundation Apache HTTP Server

    • 2.4.30 and later · up to and including 2.4.55affected · semver

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • apache http server2.4.30 and later · before 2.4.56

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8httpdbefore 2.4.37-56.module_el8.8.0+3605+a3cf1030.72.4.37-56.module_el8.8.0+3605+a3cf1030.7
AlmaLinux:8httpd-develbefore 2.4.37-56.module_el8.8.0+3605+a3cf1030.72.4.37-56.module_el8.8.0+3605+a3cf1030.7
AlmaLinux:8httpd-filesystembefore 2.4.37-56.module_el8.8.0+3605+a3cf1030.72.4.37-56.module_el8.8.0+3605+a3cf1030.7
AlmaLinux:8httpd-manualbefore 2.4.37-56.module_el8.8.0+3605+a3cf1030.72.4.37-56.module_el8.8.0+3605+a3cf1030.7
AlmaLinux:8httpd-toolsbefore 2.4.37-56.module_el8.8.0+3605+a3cf1030.72.4.37-56.module_el8.8.0+3605+a3cf1030.7
AlmaLinux:8mod_http2before 1.15.7-8.module_el8.8.0+3554+ec1058a7.31.15.7-8.module_el8.8.0+3554+ec1058a7.3
AlmaLinux:8mod_ldapbefore 2.4.37-56.module_el8.8.0+3605+a3cf1030.72.4.37-56.module_el8.8.0+3605+a3cf1030.7
AlmaLinux:8mod_mdbefore 1:2.0.8-8.module_el8.6.0+2872+fe0ff7aa1:2.0.8-8.module_el8.6.0+2872+fe0ff7aa
AlmaLinux:8mod_mdbefore 1:2.0.8-8.module_el8.6.0+3031+fb177b091:2.0.8-8.module_el8.6.0+3031+fb177b09
AlmaLinux:8mod_proxy_htmlbefore 1:2.4.37-56.module_el8.8.0+3605+a3cf1030.71:2.4.37-56.module_el8.8.0+3605+a3cf1030.7
AlmaLinux:8mod_sessionbefore 2.4.37-56.module_el8.8.0+3605+a3cf1030.72.4.37-56.module_el8.8.0+3605+a3cf1030.7
AlmaLinux:8mod_sslbefore 1:2.4.37-56.module_el8.8.0+3605+a3cf1030.71:2.4.37-56.module_el8.8.0+3605+a3cf1030.7
AlmaLinux:9httpdbefore 2.4.57-5.el92.4.57-5.el9
AlmaLinux:9httpd-corebefore 2.4.57-5.el92.4.57-5.el9
AlmaLinux:9httpd-develbefore 2.4.57-5.el92.4.57-5.el9
AlmaLinux:9httpd-filesystembefore 2.4.57-5.el92.4.57-5.el9
AlmaLinux:9httpd-manualbefore 2.4.57-5.el92.4.57-5.el9
AlmaLinux:9httpd-toolsbefore 2.4.57-5.el92.4.57-5.el9
AlmaLinux:9mod_ldapbefore 2.4.57-5.el92.4.57-5.el9
AlmaLinux:9mod_luabefore 2.4.57-5.el92.4.57-5.el9
AlmaLinux:9mod_proxy_htmlbefore 1:2.4.57-5.el91:2.4.57-5.el9
AlmaLinux:9mod_sessionbefore 2.4.57-5.el92.4.57-5.el9
AlmaLinux:9mod_sslbefore 1:2.4.57-5.el91:2.4.57-5.el9
Alpine:v3.14apache2before 2.4.56-r02.4.56-r0

+96

Same product

apache: all records

Other highest-scoring records for the same primary product.

  • CVE-2021-42013Path Traversal and Remote Code Execution in Apache HTTP Server 2.4.49 and 2.4.50 (incomplete fix of CVE-2021-41773)KEV
    99Now
  • CVE-2021-41773Path traversal and file disclosure vulnerability in Apache HTTP Server 2.4.49KEV
    99Now
  • CVE-2024-38475Apache HTTP Server weakness in mod_rewrite when first segment of substitution matches filesystem path.KEV
    96Now

Published before and after this one in the same product

  • ← EarlierCVE-2022-37436Jan 17, 2023 · Apache HTTP Server: mod_proxy prior to 2.4.55 allows a backend to trigger HTTP response splitting
    37Monitor
  • ← EarlierCVE-2023-25690Mar 7, 2023 · Apache HTTP Server: HTTP request splitting with mod_rewrite and mod_proxy
    64This week
  • Later →CVE-2023-31122Oct 23, 2023 · Apache HTTP Server: mod_macro buffer over-read
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:httpd2.4.37-56.module_el8.8.0+3605+a3cf1030.7 · AlmaLinux:8Package registry (OSV)
almalinux:httpd-core2.4.57-5.el9 · AlmaLinux:9Package registry (OSV)
almalinux:httpd-devel2.4.37-56.module_el8.8.0+3605+a3cf1030.7 · AlmaLinux:8Package registry (OSV)
almalinux:httpd-filesystem2.4.37-56.module_el8.8.0+3605+a3cf1030.7 · AlmaLinux:8Package registry (OSV)
almalinux:httpd-manual2.4.37-56.module_el8.8.0+3605+a3cf1030.7 · AlmaLinux:8Package registry (OSV)
almalinux:httpd-tools2.4.37-56.module_el8.8.0+3605+a3cf1030.7 · AlmaLinux:8Package registry (OSV)
almalinux:mod_http21.15.7-8.module_el8.8.0+3554+ec1058a7.3 · AlmaLinux:8Package registry (OSV)
almalinux:mod_ldap2.4.37-56.module_el8.8.0+3605+a3cf1030.7 · AlmaLinux:8Package registry (OSV)
almalinux:mod_md1:2.0.8-8.module_el8.6.0+2872+fe0ff7aa · AlmaLinux:8Package registry (OSV)
almalinux:mod_proxy_html1:2.4.37-56.module_el8.8.0+3605+a3cf1030.7 · AlmaLinux:8Package registry (OSV)
almalinux:mod_session2.4.37-56.module_el8.8.0+3605+a3cf1030.7 · AlmaLinux:8Package registry (OSV)
almalinux:mod_ssl1:2.4.37-56.module_el8.8.0+3605+a3cf1030.7 · AlmaLinux:8Package registry (OSV)
alpine:apache22.4.56-r0 · Alpine:v3.14Package registry (OSV)
debian:apache22.4.56-1 · Debian:12Package registry (OSV)
opensuse:apache22.4.51-150400.6.11.1 · openSUSE:Leap 15.4Package registry (OSV)
PyPI:uwsgi2.0.22Package registry (OSV)
red hat:jbcs-httpd24-apr0:1.7.0-8.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jbcs-httpd24-apr-debuginfo0:1.7.0-8.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jbcs-httpd24-apr-devel0:1.7.0-8.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jbcs-httpd24-httpd0:2.4.57-5.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jbcs-httpd24-httpd-debuginfo0:2.4.57-5.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jbcs-httpd24-httpd-devel0:2.4.57-5.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jbcs-httpd24-httpd-manual0:2.4.57-5.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jbcs-httpd24-httpd-selinux0:2.4.57-5.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jbcs-httpd24-httpd-tools0:2.4.57-5.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jbcs-httpd24-mod_ldap0:2.4.57-5.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jbcs-httpd24-mod_proxy_html1:2.4.57-5.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jbcs-httpd24-mod_session0:2.4.57-5.el7jbcs · Red Hat:jboss_core_services:1::el7Package registry (OSV)
rocky linux:httpd0:2.4.37-56.module+el8.8.0+1284+07ef499e.6 · Rocky Linux:8Package registry (OSV)
rocky linux:mod_http20:1.15.7-8.module+el8.8.0+1284+07ef499e.3 · Rocky Linux:8Package registry (OSV)

+3

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
high · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
High
Availability impact
None

Weakness class (CWE)

CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records