CVE-2016-4979

Name: CVE-2016-4979
Creator: NVD / NIST
Published: 2016-07-06T14:59:04.487+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 18.80%

Last modified Jun 17, 2026

CVE-2016-4979 is a vulnerability of currently unknown severity. The Apache HTTP Server 2.4.18 through 2.4.20, when mod_http2 and mod_ssl are enabled, does not properly recognize the "SSLVerifyClient require" directive for HTTP/2 request authorization, which allows remote attackers to bypass intended access restrictions by leveraging the ability to send multiple requests over a single connection and aborting a renegotiation.. EPSS estimates a 18.80% chance of exploitation in the next 30 days.

Description

The Apache HTTP Server 2.4.18 through 2.4.20, when mod_http2 and mod_ssl are enabled, does not properly recognize the "SSLVerifyClient require" directive for HTTP/2 request authorization, which allows remote attackers to bypass intended access restrictions by leveraging the ability to send multiple requests over a single connection and aborting a renegotiation.

Metrics

EPSS Probability

18.80%

96.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-284

Affected Software

Vendor	Product	Versions
Apache	Http Server	2.4.18
Apache	Http Server	2.4.19
Apache	Http Server	2.4.20

References

Timeline

Published: Jul 6, 2016
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2016-4979?

How severe is CVE-2016-4979?

Severity scoring for CVE-2016-4979 is pending analysis. The EPSS model estimates a 18.80% probability of exploitation in the next 30 days.

How do I fix CVE-2016-4979?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2016-4979?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST