CVE-2016-6816

CVE-2016-6816 is a high-severity vulnerability in Apache Tomcat with a CVSS 3.x base score of 7.1. Its EPSS exploit-prediction score of 40% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-20.

Key facts

Description

The code in Apache Tomcat 9.0.0.M1 to 9.0.0.M11, 8.5.0 to 8.5.6, 8.0.0.RC1 to 8.0.38, 7.0.0 to 7.0.72, and 6.0.0 to 6.0.47 that parsed the HTTP request line permitted invalid characters. This could be exploited, in conjunction with a proxy that also permitted the invalid characters but with a different interpretation, to inject data into the HTTP response. By manipulating the HTTP response the attacker could poison a web-cache, perform an XSS attack and/or obtain sensitive information from requests other then their own.

Frequently asked questions

What is CVE-2016-6816?
The code in Apache Tomcat 9.0.0.M1 to 9.0.0.M11, 8.5.0 to 8.5.6, 8.0.0.RC1 to 8.0.38, 7.0.0 to 7.0.72, and 6.0.0 to 6.0.47 that parsed the HTTP request line permitted invalid characters. This could be exploited, in conjunction with a proxy that also permitted the invalid characters but with a different interpretation, to inject data into the HTTP response. By manipulating the HTTP response the attacker could poison a web-cache, perform an XSS attack and/or obtain sensitive information from requests other then their own.
How severe is CVE-2016-6816?
CVE-2016-6816 has a CVSS 3.x base score of 7.1, rated high 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 low.
Is CVE-2016-6816 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 40% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6816?
CVE-2016-6816 primarily affects Apache Tomcat. In total, 178 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-6816?
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-2016-6816 published?
CVE-2016-6816 was published on 2017-03-20 and last updated on 2026-06-17.

References

Affected products (178)

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