CVE-2023-50269 | SQUID-2023:10 Denial of Service in HTTP Request parsing

Squid is a caching proxy for the Web. Due to an Uncontrolled Recursion bug in versions 2.6 through 2.7.STABLE9, versions 3.1 through 5.9, and versions 6.0.1 through 6.5, Squid may be vulnerable to a Denial of Service attack against HTTP Request parsing. This problem allows a remote client to perform Denial of Service attack by sending a large X-Forwarded-For header when the follow_x_forwarded_for feature is configured. This bug is fixed by Squid version 6.6. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives.

Published: 2023-12-14 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-50269 is rated High Risk (74/100): CVSS High severity, with high exploitation likelihood (EPSS 57.63%, 99th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +56.48% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize 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-2023-50269

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 2026-06-15 1.15% 57.63% +56.48%
2 2026-04-19 1.49% 1.15% -0.34%
3 2026-04-17 — 1.49% —

Full EPSS history (34 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-50269

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.6 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H 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:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 4.0 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H 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:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2023-50269

OS Trackers for CVE-2023-50269

vendor priority summary link
alpine — CVE-2023-50269: 1 source package rows (squid); 72 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 5, open 67. https://security.alpinelinux.org/vuln/CVE-2023-50269
debian not yet assigned CVE-2023-50269 not yet assigned priority: Debian including 1 source packages (squid), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2023-50269
redhat high — https://access.redhat.com/security/cve/CVE-2023-50269
suse high — https://www.suse.com/security/cve/CVE-2023-50269/
ubuntu medium CVE-2023-50269 medium priority: Ubuntu including 2 source packages (squid, squid3), 18 status rows across 9 suites (bionic, focal, jammy, lunar, mantic, noble, trusty, upstream, xenial): released 7, DNE 5, ignored 4, needs-triage 2. https://ubuntu.com/security/CVE-2023-50269

Affected software / configurations for CVE-2023-50269

Vendor Product Version Raw CPE
squid-cache squid >= 3.1, <= 5.9 cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
squid-cache squid >= 6.0.1, <= 6.5 cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
squid-cache squid 2.6 cpe:2.3:a:squid-cache:squid:2.6:*:*:*:*:*:*:*
squid-cache squid 2.7 cpe:2.3:a:squid-cache:squid:2.7:-:*:*:*:*:*:*
squid-cache squid 2.7 cpe:2.3:a:squid-cache:squid:2.7:stable1:*:*:*:*:*:*
squid-cache squid 2.7 cpe:2.3:a:squid-cache:squid:2.7:stable2:*:*:*:*:*:*
squid-cache squid 2.7 cpe:2.3:a:squid-cache:squid:2.7:stable3:*:*:*:*:*:*
squid-cache squid 2.7 cpe:2.3:a:squid-cache:squid:2.7:stable4:*:*:*:*:*:*
squid-cache squid 2.7 cpe:2.3:a:squid-cache:squid:2.7:stable5:*:*:*:*:*:*
squid-cache squid 2.7 cpe:2.3:a:squid-cache:squid:2.7:stable6:*:*:*:*:*:*
squid-cache squid 2.7 cpe:2.3:a:squid-cache:squid:2.7:stable7:*:*:*:*:*:*
squid-cache squid 2.7 cpe:2.3:a:squid-cache:squid:2.7:stable8:*:*:*:*:*:*
squid-cache squid 2.7 cpe:2.3:a:squid-cache:squid:2.7:stable9:*:*:*:*:*:*

References for CVE-2023-50269

cvelogic Threat Intelligence