CVE-2019-18676

Squid vulnerability

CVSS

7.5

EPSS

9.2%

EPSS pct

95th

Exploited

No known

An issue was discovered in Squid 3.x and 4.x through 4.8. Due to incorrect input validation, there is a heap-based buffer overflow that can result in Denial of Service to all clients using the proxy. Severity is high due to this vulnerability occurring before normal security checks; any remote client that can reach the proxy port can trivially perform the attack via a crafted URI scheme.

Affected vendor

Squid Cache

Affected product

Squid

CVSS vector

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

Weakness type (CWE)

CWE-787 — Out-of-bounds Write

Published

2019-11-26

Risk analysis

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

Its EPSS score of 9.2% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 95% of all scored CVEs.

Check your external exposure to CVE-2019-18676

Confirm whether Squid Cache Squid is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2019-18676.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2019-18676

ThreatPort's external attack surface scanner checks your internet-facing assets — agentlessly, from the outside in — for the exposed services and versions that CVE-2019-18676 affects, then prioritises the finding by real risk using CISA KEV and FIRST.org EPSS.

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