How severe is CVE-2019-18860?

CVE-2019-18860 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2019-18860 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-18860?

CVE-2019-18860 primarily affects Squid-cache Squid. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-18860?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2019-18860 published?

CVE-2019-18860 was published on 2020-03-20 and last updated on 2026-06-17.

CVE-2019-18860

CVE-2019-18860 is a medium-severity vulnerability in Squid-cache Squid with a CVSS 3.x base score of 6.1. 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-74.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 6% (93rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-74
Affected product: Squid-cache Squid
Published: 2020-03-20
Last modified: 2026-06-17

Description

Squid before 4.9, when certain web browsers are used, mishandles HTML in the host (aka hostname) parameter to cachemgr.cgi.

Frequently asked questions

What is CVE-2019-18860?: Squid before 4.9, when certain web browsers are used, mishandles HTML in the host (aka hostname) parameter to cachemgr.cgi.
How severe is CVE-2019-18860?: CVE-2019-18860 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2019-18860 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-18860?: CVE-2019-18860 primarily affects Squid-cache Squid. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-18860?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2019-18860 published?: CVE-2019-18860 was published on 2020-03-20 and last updated on 2026-06-17.

References

Affected products (8)

cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*

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Threat intelligence

Threat-intel indicators referencing this CVE:

200.89.159.59 (ipv4-addr)
39.100.85.200 (ipv4-addr)
121.43.117.198 (ipv4-addr)
39.100.82.100 (ipv4-addr)
51.159.30.56 (ipv4-addr)
39.100.84.225 (ipv4-addr)
47.95.204.107 (ipv4-addr)
192.3.127.40 (ipv4-addr)