Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2021-31807

39
FAUCET Score

CVE-2021-31807 is an integer overflow vulnerability in Squid versions before 4.15 and 5.x before 5.0.6, affecting various Fedora and NetApp products utilizing Squid. This flaw allows a remote server to trigger a Denial of Service (DoS) by crafting HTTP Range requests, utilizing a common header that doesn't inherently indicate malicious intent. With a CVSS score of 6.5 (Medium), it presents a low-complexity attack vector that can lead to high availability impact. While not actively exploited in the wild or on the CISA KEV catalog, a Metasploit module exists, and its high EPSS and FAUCET Risk Score indicate a significant potential for exploitation. Community discussion and media coverage for this CVE are minimal.

Impacted Technologies

VendorProductVersion(s)CPE
>= 3.0, < 4.15CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
>= 5.0, < 5.0.6CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
2.5.stable2CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:2.5.stable2:*:*:*:*:*:*:*
2.5.stable3CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:2.5.stable3:*:*:*:*:*:*:*
2.5.stable4CPE matchmatch criteria
cpe:2.3:a:squid-cache:squid:2.5.stable4:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
15.97%
Probability of exploitation in next 30 days
EPSS Percentile
96.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
Metasploit: Squid Proxy Range Header DoS · May 27, 2021
This CVE's current EPSS score of 0.1597 is in the 99th percentile among its peer group of 21,958 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: squid:4-8050020210618131503.b4937e53
View patch

Vendor Advisories (1)

redhatCVE-2021-31807Moderate

squid: incorrect memory management in HTTP Range header

May 10, 2021

References

seclists.org / fulldisclosure/2023/Oct/14
Mailing ListThird Party Advisory
github.com / squid-cache/squid/security/advisories/GHSA-pxwq-f3qr-w2xf
Third Party Advisory
lists.debian.org / debian-lts-announce/2021/06/msg00014.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2VCS6K3TKCF
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBTQHPBR6H66
security.netapp.com / advisory/ntap-20210716-0007
Third Party Advisory
openwall.com / lists/oss-security/2023/10/11/3
Mailing ListThird Party Advisory
squid-cache.org / Versions/v4/changesets/squid-4-e7cf864f938f24eea8af0692c04d16790983c823.patch
PatchVendor Advisory