CVE-2021-31808

Squid vulnerability

CVSS

6.5

EPSS

5.5%

EPSS pct

92th

Exploited

No known

An issue was discovered in Squid before 4.15 and 5.x before 5.0.6. Due to an input-validation bug, it is vulnerable to a Denial of Service attack (against all clients using the proxy). A client sends an HTTP Range request to trigger this.

Affected vendor

Squid Cache

Affected product

Squid

CVSS vector

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

Weakness type (CWE)

CWE-190 — Integer Overflow or Wraparound

Published

2021-05-27

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring low privileges, no user interaction. Successful exploitation leads to high impact to availability.

Its EPSS score of 5.5% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 92% of all scored CVEs.

Check your external exposure to CVE-2021-31808

Confirm whether Squid Cache Squid is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2021-31808.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2021-31808

ThreatPort's external attack surface scanner checks your internet-facing assets — agentlessly, from the outside in — for the exposed services and versions that CVE-2021-31808 affects, then prioritises the finding by real risk using CISA KEV and FIRST.org EPSS.

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Are you exposed to CVE-2021-31808?

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