SQUID-2023:10 Denial of Service in HTTP Request parsing
Priority HIGH 77CWE-674Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 16 fixed, 1 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-674.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.57627 99th percentileScored 2026-11-07
Fix Partial squid (squid-cache): 6.6Red Hat: 9 advisoriesRed Hat: 16 fixed, 1 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| squid-cache | squid | 2.6 – 2.7.STABLE9; 3.1 – 5.9; 6.0.1 to before 6.6 | 6.6 | Patch available | CNA |
- squid Vendorsquid-cache Affected 2.6 – 2.7.STABLE9; 3.1 – 5.9; 6.0.1 to before 6.6 Fixed in 6.6 Patch available CNA
CPE configurations NVD · 12
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:* | 3.1 – 5.9; 6.0.1 – 6.5 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.6:*:*:*:*:*:*:* | 2.6 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.7:-:*:*:*:*:*:* | 2.7 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.7:stable1:*:*:*:*:*:* | 2.7 stable1 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.7:stable2:*:*:*:*:*:* | 2.7 stable2 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.7:stable3:*:*:*:*:*:* | 2.7 stable3 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.7:stable4:*:*:*:*:*:* | 2.7 stable4 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.7:stable5:*:*:*:*:*:* | 2.7 stable5 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.7:stable6:*:*:*:*:*:* | 2.7 stable6 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.7:stable7:*:*:*:*:*:* | 2.7 stable7 | Vulnerable | squid-cache |
- cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:* Versions 3.1 – 5.9; 6.0.1 – 6.5 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.6:*:*:*:*:*:*:* Versions 2.6 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.7:-:*:*:*:*:*:* Versions 2.7 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.7:stable1:*:*:*:*:*:* Versions 2.7 stable1 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.7:stable2:*:*:*:*:*:* Versions 2.7 stable2 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.7:stable3:*:*:*:*:*:* Versions 2.7 stable3 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.7:stable4:*:*:*:*:*:* Versions 2.7 stable4 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.7:stable5:*:*:*:*:*:* Versions 2.7 stable5 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.7:stable6:*:*:*:*:*:* Versions 2.7 stable6 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.7:stable7:*:*:*:*:*:* Versions 2.7 stable7 Vulnerable ·squid-cache
Show 2 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:squid-cache:squid:2.7:stable8:*:*:*:*:*:* | 2.7 stable8 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.7:stable9:*:*:*:*:*:* | 2.7 stable9 | Vulnerable | squid-cache |
- cpe:2.3:a:squid-cache:squid:2.7:stable8:*:*:*:*:*:* Versions 2.7 stable8 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.7:stable9:*:*:*:*:*:* Versions 2.7 stable9 Vulnerable ·squid-cache
Remediation
- Fix · CNA squid (squid-cache) Fixed in 6.6
Red Hat 9 advisories
- RHSA-2024:1787 Released 2024-04-11 · Red Hat rating Importantsquid security update
- Red Hat Enterprise Linux Server (v. 7) squid-7:3.5.20-17.el7_9.10, squid-migration-script-7:3.5.20-17.el7_9.10
- Red Hat Enterprise Linux Server Optional (v. 7) squid-sysvinit-7:3.5.20-17.el7_9.10
- Red Hat Enterprise Linux Workstation (v. 7) squid-7:3.5.20-17.el7_9.10, squid-migration-script-7:3.5.20-17.el7_9.10
- Red Hat Enterprise Linux Workstation Optional (v. 7) squid-sysvinit-7:3.5.20-17.el7_9.10
- RHSA-2024:1375 Released 2024-03-19 · Red Hat rating Importantsquid:4 security update
- Red Hat Enterprise Linux AppStream (v. 8) libecap-1.0.1-2.module+el8.9.0+19703+a1da7223.aarch64::squid:4, libecap-1.0.1-2.module+el8.9.0+19703+a1da7223.ppc64le::squid:4, libecap-1.0.1-2.module+el8.9.0+19703+a1da7223.s390x::squid:4 +11
- RHSA-2024:1376 Released 2024-03-19 · Red Hat rating Importantsquid security update
- Red Hat Enterprise Linux AppStream (v. 9) squid-7:5.5-6.el9_3.8
Show 6 more Red Hat advisories
- RHSA-2024:1153 Released 2024-03-05 · Red Hat rating Importantsquid security update
- Red Hat Enterprise Linux AppStream EUS (v.9.0) squid-7:5.2-1.el9_0.4
- RHSA-2024:1085 Released 2024-03-05 · Red Hat rating Importantsquid security update
- Red Hat Enterprise Linux AppStream EUS (v.9.2) squid-7:5.5-5.el9_2.4
- RHSA-2024:0771 Released 2024-02-12 · Red Hat rating Importantsquid:4 security update
- Red Hat Enterprise Linux AppStream EUS (v.8.6) libecap-1.0.1-2.module+el8.1.0+4044+36416a77.aarch64::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.ppc64le::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.s390x::squid:4 +11
- RHSA-2024:0773 Released 2024-02-12 · Red Hat rating Importantsquid:4 security update
- Red Hat Enterprise Linux AppStream AUS (v.8.4) libecap-1.0.1-2.module+el8.1.0+4044+36416a77.src::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.x86_64::squid:4, libecap-devel-1.0.1-2.module+el8.1.0+4044+36416a77.x86_64::squid:4 +2
- Red Hat Enterprise Linux AppStream E4S (v.8.4) libecap-1.0.1-2.module+el8.1.0+4044+36416a77.ppc64le::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.src::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.x86_64::squid:4 +5
- Red Hat Enterprise Linux AppStream TUS (v.8.4) libecap-1.0.1-2.module+el8.1.0+4044+36416a77.src::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.x86_64::squid:4, libecap-devel-1.0.1-2.module+el8.1.0+4044+36416a77.x86_64::squid:4 +2
- RHSA-2024:0772 Released 2024-02-12 · Red Hat rating Importantsquid:4 security update
- Red Hat Enterprise Linux AppStream AUS (v. 8.2) libecap-1.0.1-2.module+el8.1.0+4044+36416a77.src::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.x86_64::squid:4, libecap-devel-1.0.1-2.module+el8.1.0+4044+36416a77.x86_64::squid:4 +2
- Red Hat Enterprise Linux AppStream E4S (v. 8.2) libecap-1.0.1-2.module+el8.1.0+4044+36416a77.ppc64le::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.src::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.x86_64::squid:4 +5
- Red Hat Enterprise Linux AppStream TUS (v. 8.2) libecap-1.0.1-2.module+el8.1.0+4044+36416a77.src::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.x86_64::squid:4, libecap-devel-1.0.1-2.module+el8.1.0+4044+36416a77.x86_64::squid:4 +2
- RHSA-2024:0397 Released 2024-01-24 · Red Hat rating Importantsquid:4 security update
- Red Hat Enterprise Linux AppStream EUS (v.8.8) libecap-1.0.1-2.module+el8.1.0+4044+36416a77.aarch64::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.ppc64le::squid:4, libecap-1.0.1-2.module+el8.1.0+4044+36416a77.s390x::squid:4 +11
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2024:1375 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2024:1376 |
| Red Hat Enterprise Linux AppStream AUS (v. 8.2) | Fixed | RHSA-2024:0772 |
| Red Hat Enterprise Linux AppStream AUS (v.8.4) | Fixed | RHSA-2024:0773 |
| Red Hat Enterprise Linux AppStream E4S (v. 8.2) | Fixed | RHSA-2024:0772 |
| Red Hat Enterprise Linux AppStream E4S (v.8.4) | Fixed | RHSA-2024:0773 |
| Red Hat Enterprise Linux AppStream EUS (v.8.6) | Fixed | RHSA-2024:0771 |
| Red Hat Enterprise Linux AppStream EUS (v.8.8) | Fixed | RHSA-2024:0397 |
| Red Hat Enterprise Linux AppStream EUS (v.9.0) | Fixed | RHSA-2024:1153 |
| Red Hat Enterprise Linux AppStream EUS (v.9.2) | Fixed | RHSA-2024:1085 |
| Red Hat Enterprise Linux AppStream TUS (v. 8.2) | Fixed | RHSA-2024:0772 |
| Red Hat Enterprise Linux AppStream TUS (v.8.4) | Fixed | RHSA-2024:0773 |
| Red Hat Enterprise Linux Server (v. 7) | Fixed | RHSA-2024:1787 |
| Red Hat Enterprise Linux Server Optional (v. 7) | Fixed | RHSA-2024:1787 |
| Red Hat Enterprise Linux Workstation (v. 7) | Fixed | RHSA-2024:1787 |
| Red Hat Enterprise Linux Workstation Optional (v. 7) | Fixed | RHSA-2024:1787 |
Timeline
- 2026-10-02 Threatist record created from CVE-2023-50269
References
Other 6
- http://www.squid-cache.org/Versions/v5/SQUID-2023_10.patch
- http://www.squid-cache.org/Versions/v6/SQUID-2023_10.patch
- https://lists.fedoraproject.org/archives/list/[email protected]/message/MEV66D3PAAY6K7TWDT3WZBLCPLASFJDC/
- https://lists.fedoraproject.org/archives/list/[email protected]/message/A5QASTMCUSUEW3UOMKHZJB3FTONWSRXS/
- https://lists.debian.org/debian-lts-announce/2024/01/msg00003.html
- https://security.netapp.com/advisory/ntap-20240119-0005/
More squid-cache Squid vulnerabilities
- TI-2025-38486 Squid vulnerable to information disclosure via authentication credential leakage in error handling CVSS 3.1CRITICAL 10.0
- TI-2024-16845 Denial of Service in HTTP Header parser in squid proxy CVSS 3.1HIGH 7.5
- TI-2024-16566 SQUID-2024:1 Denial of Service in HTTP Chunked Decoding CVSS 3.1HIGH 8.6
- TI-2023-26921 Denial of Service in HTTP Message Processing in Squid CVSS 3.1HIGH 8.6
- TI-2023-25306 Squid: denial of service in http digest authentication CVSS 3.1HIGH 8.6
- TI-2016-03919 client_side.cc in Squid before 3.5.18 and 4.x before 4.0.10 does not properly ignore the… CVSS 3.0HIGH 8.6
Sources
- CVE-2023-50269 · CVE Program
- CVE-2023-50269 · NVD
- FIRST EPSS
- CVE-2023-50269 · Red Hat security data · CC BY 4.0
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