An issue was discovered in Squid before 4.15 and 5.x before 5.0.6.
Priority MEDIUM 45CWE-190Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 1 fixed, 2 without a fix
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-190 and the CVSS impact.
Summary
An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. An integer overflow problem allows a remote server to achieve Denial of Service when delivering responses to HTTP Range requests. The issue trigger is a header that can be expected to exist in HTTP traffic without any malicious intent.
Why it matters now
EPSS 0.15559 96th percentileScored 2026-11-07
Fix Partial Red Hat: 1 advisoryRed Hat: 1 fixed, 2 without a fix
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 27
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:* | 3.0 to before 4.15; 5.0 to before 5.0.6 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable2:*:*:*:*:*:*:* | 2.5.stable2 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable3:*:*:*:*:*:*:* | 2.5.stable3 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable4:*:*:*:*:*:*:* | 2.5.stable4 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable5:*:*:*:*:*:*:* | 2.5.stable5 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable6:*:*:*:*:*:*:* | 2.5.stable6 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable7:*:*:*:*:*:*:* | 2.5.stable7 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable8:*:*:*:*:*:*:* | 2.5.stable8 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable9:*:*:*:*:*:*:* | 2.5.stable9 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable10:*:*:*:*:*:*:* | 2.5.stable10 | Vulnerable | squid-cache |
- cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:* Versions 3.0 to before 4.15; 5.0 to before 5.0.6 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable2:*:*:*:*:*:*:* Versions 2.5.stable2 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable3:*:*:*:*:*:*:* Versions 2.5.stable3 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable4:*:*:*:*:*:*:* Versions 2.5.stable4 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable5:*:*:*:*:*:*:* Versions 2.5.stable5 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable6:*:*:*:*:*:*:* Versions 2.5.stable6 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable7:*:*:*:*:*:*:* Versions 2.5.stable7 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable8:*:*:*:*:*:*:* Versions 2.5.stable8 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable9:*:*:*:*:*:*:* Versions 2.5.stable9 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable10:*:*:*:*:*:*:* Versions 2.5.stable10 Vulnerable ·squid-cache
Show 17 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:squid-cache:squid:2.5.stable11:*:*:*:*:*:*:* | 2.5.stable11 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable12:*:*:*:*:*:*:* | 2.5.stable12 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable13:*:*:*:*:*:*:* | 2.5.stable13 | Vulnerable | squid-cache |
| cpe:2.3:a:squid-cache:squid:2.5.stable14:*:*:*:*:*:*:* | 2.5.stable14 | 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: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: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:o:fedoraproject:fedora:33:*:*:*:*:*:*:* | 33 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* | 34 | Vulnerable | Fedoraproject |
| cpe:2.3:a:netapp:cloud_manager:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | NetApp |
- cpe:2.3:a:squid-cache:squid:2.5.stable11:*:*:*:*:*:*:* Versions 2.5.stable11 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable12:*:*:*:*:*:*:* Versions 2.5.stable12 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable13:*:*:*:*:*:*:* Versions 2.5.stable13 Vulnerable ·squid-cache
- cpe:2.3:a:squid-cache:squid:2.5.stable14:*:*:*:*:*:*:* Versions 2.5.stable14 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: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
- 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
- cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* Versions 33 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
- cpe:2.3:a:netapp:cloud_manager:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·NetApp
Remediation
Red Hat 1 advisory
- RHSA-2021:4292 Released 2021-11-09 · Red Hat rating Moderatesquid:4 security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 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: Moderate. 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 7 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux AppStream (v. 8) | Fixed | RHSA-2021:4292 |
Not affected: 1 product
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2021-31807
- 2026-10-03 Alias added: GHSA-34v2-m9jr-2wg3
References
Advisory 7
- https://github.com/squid-cache/squid/security/advisories/GHSA-pxwq-f3qr-w2xf
- FEDORA-2021-c0bec55ec7
- FEDORA-2021-24af72ff2c
- [debian-lts-announce] 20210614 [SECURITY] [DLA 2685-1] squid3 security update
- https://security.netapp.com/advisory/ntap-20210716-0007/
- [oss-security] 20231011 Squid Caching Proxy Security Audit: 55 Vulnerabilities, 35 0days.
- 20231016 Squid Caching Proxy Security Audit: 55 Vulnerabilities, 35 0days.
Sources
- CVE-2021-31807 · CVE Program
- CVE-2021-31807 · NVD
- FIRST EPSS
- GHSA-34v2-m9jr-2wg3 · GitHub Advisory Database · CC BY 4.0
- CVE-2021-31807 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences