How severe is CVE-2019-18679?

CVE-2019-18679 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2019-18679 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 41% (98th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-18679?

CVE-2019-18679 primarily affects Squid-cache Squid. In total, 16 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-18679?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2019-18679 published?

CVE-2019-18679 was published on 2019-11-26 and last updated on 2026-06-17.

CVE-2019-18679

CVE-2019-18679 is a high-severity vulnerability in Squid-cache Squid with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 41% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-200.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 41% (98th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-200
Affected product: Squid-cache Squid
Published: 2019-11-26
Last modified: 2026-06-17

Description

An issue was discovered in Squid 2.x, 3.x, and 4.x through 4.8. Due to incorrect data management, it is vulnerable to information disclosure when processing HTTP Digest Authentication. Nonce tokens contain the raw byte value of a pointer that sits within heap memory allocation. This information reduces ASLR protections and may aid attackers isolating memory areas to target for remote code execution attacks.

Frequently asked questions

What is CVE-2019-18679?: An issue was discovered in Squid 2.x, 3.x, and 4.x through 4.8. Due to incorrect data management, it is vulnerable to information disclosure when processing HTTP Digest Authentication. Nonce tokens contain the raw byte value of a pointer that sits within heap memory allocation. This information reduces ASLR protections and may aid attackers isolating memory areas to target for remote code execution attacks.
How severe is CVE-2019-18679?: CVE-2019-18679 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2019-18679 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 41% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-18679?: CVE-2019-18679 primarily affects Squid-cache Squid. In total, 16 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-18679?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2019-18679 published?: CVE-2019-18679 was published on 2019-11-26 and last updated on 2026-06-17.

References

Affected products (16)

cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:2.7:stable2:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:2.7:stable3:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:2.7:stable4:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:2.7:stable5:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:2.7:stable6:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:2.7:stable7:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:2.7:stable8:*:*:*:*:*:*
cpe:2.3:a:squid-cache:squid:2.7:stable9:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:19.04:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*

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Threat intelligence

Threat-intel indicators referencing this CVE:

200.89.159.59 (ipv4-addr)
192.3.127.40 (ipv4-addr)