How severe is CVE-2020-8449?

CVE-2020-8449 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-2020-8449 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-8449?

CVE-2020-8449 primarily affects Squid-cache Squid. In total, 9 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-8449?

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-2020-8449 published?

CVE-2020-8449 was published on 2020-02-04 and last updated on 2026-06-17.

CVE-2020-8449

CVE-2020-8449 is a high-severity vulnerability in Squid-cache Squid with a CVSS 3.x base score of 7.5. 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-668.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 8% (94th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-668
Affected product: Squid-cache Squid
Published: 2020-02-04
Last modified: 2026-06-17

Description

An issue was discovered in Squid before 4.10. Due to incorrect input validation, it can interpret crafted HTTP requests in unexpected ways to access server resources prohibited by earlier security filters.

Frequently asked questions

What is CVE-2020-8449?: An issue was discovered in Squid before 4.10. Due to incorrect input validation, it can interpret crafted HTTP requests in unexpected ways to access server resources prohibited by earlier security filters.
How severe is CVE-2020-8449?: CVE-2020-8449 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-2020-8449 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-8449?: CVE-2020-8449 primarily affects Squid-cache Squid. In total, 9 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-8449?: 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-2020-8449 published?: CVE-2020-8449 was published on 2020-02-04 and last updated on 2026-06-17.

References

Affected products (9)

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:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:19.10:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*

More vulnerabilities in Squid-cache Squid

CVE-2025-62168 — Critical (CVSS 10.0): Squid is a caching proxy for the Web. In Squid versions prior to 7.2, a failure to redact HTTP authentication…
CVE-2020-15049 — Critical (CVSS 9.9): An issue was discovered in http/ContentLengthInterpreter.cc in Squid before 4.12 and 5.x before 5.0.3. A Request…
CVE-2020-11945 — Critical (CVSS 9.8): An issue was discovered in Squid before 5.0.2. A remote attacker can replay a sniffed Digest Authentication nonce to…
CVE-2019-12519 — Critical (CVSS 9.8): An issue was discovered in Squid through 4.7. When handling the tag esi:when when ESI is enabled, Squid calls…
CVE-2019-12524 — Critical (CVSS 9.8): An issue was discovered in Squid through 4.7. When handling requests from users, Squid checks its rules to see if the…
CVE-2019-12526 — Critical (CVSS 9.8): An issue was discovered in Squid before 4.9. URN response handling in Squid suffers from a heap-based buffer overflow.…

All CVEs affecting Squid-cache Squid →

Other CWE-668 (Exposure of Resource to Wrong Sphere) vulnerabilities

CVE-2025-2857 — Critical (CVSS 10.0): Following the recent Chrome sandbox escape (CVE-2025-2783), various Firefox developers identified a similar pattern in…
CVE-2019-8779 — Critical (CVSS 10.0): A logic issue applied the incorrect restrictions. This issue was addressed by updating the logic to apply the correct…
CVE-2012-1846 — Critical (CVSS 10.0): Google Chrome 17.0.963.66 and earlier allows remote attackers to bypass the sandbox protection mechanism by leveraging…
CVE-2022-43684 — Critical (CVSS 9.9): ServiceNow has released patches and an upgrade that address an Access Control List (ACL) bypass issue in ServiceNow…
CVE-2022-24900 — Critical (CVSS 9.9): Piano LED Visualizer is software that allows LED lights to light up as a person plays a piano connected to a computer.…
CVE-2019-16541 — Critical (CVSS 9.9): Jenkins JIRA Plugin 3.0.10 and earlier does not declare the correct (folder) scope for per-folder Jira site…

Browse all CWE-668 (Exposure of Resource to Wrong Sphere) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

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