CVE-2019-12524

CVE-2019-12524 is a critical-severity vulnerability in Squid-cache Squid with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-306.

Key facts

Description

An issue was discovered in Squid through 4.7. When handling requests from users, Squid checks its rules to see if the request should be denied. Squid by default comes with rules to block access to the Cache Manager, which serves detailed server information meant for the maintainer. This rule is implemented via url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to encode their URL to bypass the url_regex check, and gain access to the blocked resource.

Frequently asked questions

What is CVE-2019-12524?
An issue was discovered in Squid through 4.7. When handling requests from users, Squid checks its rules to see if the request should be denied. Squid by default comes with rules to block access to the Cache Manager, which serves detailed server information meant for the maintainer. This rule is implemented via url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to encode their URL to bypass the url_regex check, and gain access to the blocked resource.
How severe is CVE-2019-12524?
CVE-2019-12524 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2019-12524 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (90th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-12524?
CVE-2019-12524 primarily affects Squid-cache Squid. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-12524?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2019-12524 published?
CVE-2019-12524 was published on 2020-04-15 and last updated on 2026-06-17.

References

Affected products (5)

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Threat intelligence

Threat-intel indicators referencing this CVE: