HOMEVULNERABILITIESCVE-2021-31807
MEDIUM

CVE-2021-31807

CWE-190Published: June 8, 2021· Updated: Jun 17, 2026

6.5
CVSS v3.1

Official Description

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.

NVD Source

Technical Analysis

CVE-2021-31807 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.Low
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

Fedora1 product(s)
fedora
netapp1 product(s)
cloud manager
squid-cache1 product(s)
squid
Source: NVD CPE · 19 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttp://www.squid-cache.org/Versions/v4/changesets/squid-4-e7cf864f938f24eea8af0692c04d16790983c823.patch
PATCHhttp://www.squid-cache.org/Versions/v4/changesets/squid-4-e7cf864f938f24eea8af0692c04d16790983c823.patch
ADVISORYhttp://seclists.org/fulldisclosure/2023/Oct/14
ADVISORYhttp://www.openwall.com/lists/oss-security/2023/10/11/3
ADVISORYhttps://github.com/squid-cache/squid/security/advisories/GHSA-pxwq-f3qr-w2xf
ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/06/msg00014.html
ADVISORYhttps://security.netapp.com/advisory/ntap-20210716-0007/
ADVISORYhttp://seclists.org/fulldisclosure/2023/Oct/14
ADVISORYhttp://www.openwall.com/lists/oss-security/2023/10/11/3
ADVISORYhttps://github.com/squid-cache/squid/security/advisories/GHSA-pxwq-f3qr-w2xf
ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/06/msg00014.html
ADVISORYhttps://security.netapp.com/advisory/ntap-20210716-0007/

All References (16)

→
http://seclists.org/fulldisclosure/2023/Oct/14Mailing List · Third Party Advisory
→
http://www.openwall.com/lists/oss-security/2023/10/11/3Mailing List · Third Party Advisory
→
http://www.squid-cache.org/Versions/v4/changesets/squid-4-e7cf864f938f24eea8af0692c04d16790983c823.patchPatch · Vendor Advisory
→
https://github.com/squid-cache/squid/security/advisories/GHSA-pxwq-f3qr-w2xfThird Party Advisory
→
https://lists.debian.org/debian-lts-announce/2021/06/msg00014.htmlMailing List · Third Party Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2VCS6K3TKCF/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBTQHPBR6H66/
→
https://security.netapp.com/advisory/ntap-20210716-0007/Third Party Advisory
→
http://seclists.org/fulldisclosure/2023/Oct/14Mailing List · Third Party Advisory
→
http://www.openwall.com/lists/oss-security/2023/10/11/3Mailing List · Third Party Advisory
→
http://www.squid-cache.org/Versions/v4/changesets/squid-4-e7cf864f938f24eea8af0692c04d16790983c823.patchPatch · Vendor Advisory
→
https://github.com/squid-cache/squid/security/advisories/GHSA-pxwq-f3qr-w2xfThird Party Advisory
→
https://lists.debian.org/debian-lts-announce/2021/06/msg00014.htmlMailing List · Third Party Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2VCS6K3TKCF/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBTQHPBR6H66/

Quick Facts

CVE IDCVE-2021-31807
CVSS Score6.5 / 10
SeverityMEDIUM
WeaknessCWE-190
CISA KEVNo
Affected3 vendor(s)
PublishedJun 8, 2021

Related CVEs (CWE-190)

CVE-2012-5835
10.0
CVE-2013-2555
10.0
CVE-2008-2663
10.0
CVE-2010-1233
10.0
CVE-2010-3254
10.0
CVE-2015-5108
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-31807 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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