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

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: 2023-03-07 Last update: 2025-05-01 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-27522 is rated Moderate Risk (54.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.67%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-27522

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-17 0.78% 0.67% -0.11%
2 2026-03-25 0.64% 0.78% +0.14%
3 2026-02-19 — 0.64% —

Full EPSS history (40 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-27522

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2023-27522

GitHub Security Advisory for CVE-2023-27522

GHSA-vcph-37mh-fqrh · Severity: high · Ecosystem: pip — Apache HTTP Server via mod_proxy_uwsgi HTTP response smuggling

OS Trackers for CVE-2023-27522

vendor priority summary link
alpine — CVE-2023-27522: 1 source package rows (apache2); 7 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 0. https://security.alpinelinux.org/vuln/CVE-2023-27522
debian not yet assigned CVE-2023-27522 not yet assigned priority: Debian including 1 source packages (apache2), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-27522
gentoo low CVE-2023-27522: 1 GLSA(s) (202309-01), 1 atom(s) (www-servers/apache); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-27522
redhat medium — https://access.redhat.com/security/cve/CVE-2023-27522
suse medium CVE-2023-27522 severity moderate: SUSE including 333 source package names (2.8-13.5:apache2-utils-2.4.51-150400.6.11.1, 4.3.6.9.31.1:apache2-2.4.51-150400.6.11.1, …), 596 product×package rows across 88 product lines (Container bci/php-apache, Container suse/manager/4.3/proxy-httpd, … (88 product lines)): Fixed 326, Known Affected 231, Known Not Affected 39. https://www.suse.com/security/cve/CVE-2023-27522/
ubuntu medium CVE-2023-27522 medium priority: Ubuntu including 1 source packages (apache2), 8 status rows across 8 suites (bionic, focal, jammy, kinetic, lunar, trusty, upstream, xenial): released 5, not-affected 3. https://ubuntu.com/security/CVE-2023-27522

Affected software / configurations for CVE-2023-27522

Vendor Product Version Raw CPE
apache http_server >= 2.4.30, < 2.4.56 cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
unbit uwsgi < 2.0.22 cpe:2.3:a:unbit:uwsgi:*:*:*:*:*:*:*:*

References for CVE-2023-27522

cvelogic Threat Intelligence