cbcvebase.
CVE-2021-31806
published 2021-05-27

CVE-2021-31806: 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…

PriorityP262medium6.5CVSS 3.1
AVNACLPRLUINSUCNINAH
EXPLOIT
EPSS
95.78%
99.9th percentile
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.

Affected

12 ranges
VendorProductVersion rangeFixed in
debiandebian_linux
debiandebian_linux
debiansquid< squid 4.13-10 (bookworm)squid 4.13-10 (bookworm)
fedoraprojectfedora
fedoraprojectfedora
squid-cachesquid< 4.154.15
squid-cachesquid>= 5.0 < 5.0.65.0.6
squidsquid>= 0 < 4.13-104.13-10
squidsquid>= 0 < 4.13-104.13-10
squidsquid>= 0 < 4.13-104.13-10
squidsquid>= 0 < 4.13-104.13-10
squidsquid>= 0 < 4.10-1ubuntu1.44.10-1ubuntu1.4

Detection & IOCsextracted from sources · hover to see the quote

commandHTTP Range header with crafted range values triggering memory-management bug in Squid
  • Monitor for anomalous or crafted HTTP Range request headers sent to Squid proxy instances (versions 3.0–4.14 and 5.0.1–5.0.5); these are the attack vector for triggering the DoS.
  • A Metasploit auxiliary module (dos/http/squid_range_dos) exists for this CVE; detect exploitation attempts by correlating Squid crashes or memory errors with inbound HTTP Range header traffic.
  • Improper input validation in the HTTP Range header is the root cause; inspect and alert on malformed or unusually large/complex Range header values in proxy traffic.
  • ·Red Hat Satellite is not affected because its squid.conf disables all http_access fragments except localhost, limiting exposure to local traffic only.
  • ·Affected Squid versions are before 4.15 and 5.x before 5.0.6; deployments on these versions are vulnerable and should be patched or mitigated.

CVSS provenance

nvdv3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
nvdv2.04.0MEDIUMAV:N/AC:L/Au:S/C:N/I:N/A:P
osv7.5HIGH
vendor_ubuntu7.5HIGH
vendor_debian6.5MEDIUM
vendor_redhat6.5MEDIUM
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