CVE-2021-31806: debian debian_linux Improper Encoding or Escaping of Output
Vulnerability summary
CVE-2021-31806 is a medium (CVSS 6.5) Improper Encoding or Escaping of Output vulnerability in debian debian_linux. EPSS estimates a 95.33% chance of exploitation in the next 30 days, higher than 99.8% of scored vulnerabilities. 1 public exploit is recorded.
Advisory lineage
Upstream 0 · Downstream 10 · Related 6Timeline
- 27-05-2021PublishedVulnerability first disclosed.
- 03-08-2024Last modifiedVulnerability information updated.
Description
An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due to a memory-management bug, it is vulnerable to a Denial of Service attack (against all clients using the proxy) via HTTP Range request processing.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · AlpineEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · UbuntuEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated6.5MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
95.33%
Chance of exploitation in the next 30 days
Percentile
100%
Versus all other CVEs
30-day change
-0.45 pp
From 95.78% on 18-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
1 foundSquid Proxy Range Header DoS
auxiliary/dos/http/squid_range_dos
Maturity: poc
Weaknesses
CWE · root causeAffected systems
Debian2 products
- squid< 4.13-10
- debian_linuxEOL9.0 | 10.0
Ubuntu2 products
- squid< 4.10-1ubuntu1.4
- squid3All versions (No fix recorded) | < 3.5.27-1ubuntu1.11
Alpine1 product
- squid≥ 5.0, < 4.15-r0 | ≥ 5.0, < 5.0.6-r0
Fedoraproject1 product
- fedoraEOL33 | 34
Netapp1 product
Squid-cache1 product
- squid< 4.15 | ≥ 5.0, < 5.0.6
6 vendors · 8 products
References
14 links
- lists.fedoraproject.org/archives/…Vendor Advisory
- lists.fedoraproject.org/archives/…Vendor Advisory
- security.netapp.com/advisory/ntap-20210716-0007/Third Party Advisory