CVE-2016-4979 in the critical feed json
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 requ…
published 2016-07-06 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-5947
- cvss
- 7.5
- version 3.0, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 18.8%
- EPSS 18.8% chance of exploitation in 30 days, percentile 97%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- apache2 Debian 14, Debian 13, Debian 12 2.4.23-1
debian advisories DEBIAN-CVE-2016-4979
- httpd24-httpd RHEL 2 SOFTWARE_COLLECTIONS 2.4.18-11.el6
- httpd24-httpd RHEL 2 SOFTWARE_COLLECTIONS 2.4.18-11.el7
- httpd24-mod_ssl RHEL 2 SOFTWARE_COLLECTIONS 1:2.4.18-11.el6
- httpd24-mod_ssl RHEL 2 SOFTWARE_COLLECTIONS 1:2.4.18-11.el7
- httpd24-mod_ldap RHEL 2 SOFTWARE_COLLECTIONS 2.4.18-11.el6
- httpd24-mod_ldap RHEL 2 SOFTWARE_COLLECTIONS 2.4.18-11.el7
- httpd24-httpd-tools RHEL 2 SOFTWARE_COLLECTIONS 2.4.18-11.el6
- httpd24-httpd-tools RHEL 2 SOFTWARE_COLLECTIONS 2.4.18-11.el7
red hat advisories RHSA-2016:1420
- apache2 openSUSE Tumbleweed 2.4.23-4.1
opensuse advisories openSUSE-SU-2024:10268-1
Vendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2016-4979 updated cvss 9.1
httpd: X509 client certificate authentication bypass using HTTP/2
-
Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 6) httpd24-httpd 2.4.18-11.el6, httpd24-mod_ssl 2.4.18-11.el6, httpd24-mod_ldap 2.4.18-11.el6, httpd24-httpd-tools 2.4.18-11.el6, httpd24-mod_session 2.4.18-11.el6, httpd24-httpd-manual 2.4.18-11.el6, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) httpd24-httpd 2.4.18-11.el7, httpd24-mod_ssl 2.4.18-11.el7, httpd24-mod_ldap 2.4.18-11.el7, httpd24-httpd-tools 2.4.18-11.el7, httpd24-mod_session 2.4.18-11.el7, httpd24-httpd-manual 2.4.18-11.el7, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 6.6) httpd24-httpd 2.4.18-11.el6, httpd24-mod_ssl 2.4.18-11.el6, httpd24-mod_ldap 2.4.18-11.el6, httpd24-httpd-tools 2.4.18-11.el6, httpd24-mod_session 2.4.18-11.el6, httpd24-httpd-manual 2.4.18-11.el6, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 6.7) httpd24-httpd 2.4.18-11.el6, httpd24-mod_ssl 2.4.18-11.el6, httpd24-mod_ldap 2.4.18-11.el6, httpd24-httpd-tools 2.4.18-11.el6, httpd24-mod_session 2.4.18-11.el6, httpd24-httpd-manual 2.4.18-11.el6, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.1) httpd24-httpd 2.4.18-11.el7, httpd24-mod_ssl 2.4.18-11.el7, httpd24-mod_ldap 2.4.18-11.el7, httpd24-httpd-tools 2.4.18-11.el7, httpd24-mod_session 2.4.18-11.el7, httpd24-httpd-manual 2.4.18-11.el7, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.2) httpd24-httpd 2.4.18-11.el7, httpd24-mod_ssl 2.4.18-11.el7, httpd24-mod_ldap 2.4.18-11.el7, httpd24-httpd-tools 2.4.18-11.el7, httpd24-mod_session 2.4.18-11.el7, httpd24-httpd-manual 2.4.18-11.el7, +1 morefixed: vendor fix RHSA-2016:1420
+2 more productsfewer
Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 6) httpd24-httpd 2.4.18-11.el6, httpd24-mod_ssl 2.4.18-11.el6, httpd24-mod_ldap 2.4.18-11.el6, httpd24-httpd-tools 2.4.18-11.el6, httpd24-mod_session 2.4.18-11.el6, httpd24-httpd-manual 2.4.18-11.el6, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) httpd24-httpd 2.4.18-11.el7, httpd24-mod_ssl 2.4.18-11.el7, httpd24-mod_ldap 2.4.18-11.el7, httpd24-httpd-tools 2.4.18-11.el7, httpd24-mod_session 2.4.18-11.el7, httpd24-httpd-manual 2.4.18-11.el7, +1 more -
Red Hat Directory Server 8 httpd Red Hat Enterprise Linux 5 httpd Red Hat Enterprise Linux 6 httpd, mod_ssl, httpd-tools, httpd-manual Red Hat Enterprise Linux 7 httpd, mod_ssl, mod_ldap, httpd-tools, mod_session, httpd-manual, +1 more Red Hat JBoss Core Services jbcs-httpd24-httpd jbcs-httpd24-httpd Red Hat JBoss Enterprise Application Platform 5 httpdnot affected: vulnerable code not present
+4 more productsfewer
Red Hat JBoss Enterprise Application Platform 6 httpd, mod_ssl, mod_ldap, httpd-tools, httpd-manual, httpd22 httpd22 Red Hat JBoss Enterprise Web Server 1 httpd Red Hat JBoss Enterprise Web Server 2 jbcs-httpd24, jbcs-httpd24-runtime Red Hat JBoss Enterprise Web Server 3 httpd
Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf
Exploit prediction
18.80% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.0 | 7.5 | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
| NVD | 2.0 | 5.0 | AV:N/AC:L/Au:N/C:N/I:P/A:N |
Classification
- Weakness
-
- CWE-284 Improper Access Control
- Technology feeds
References
- github.com /apache/httpd/commit/2d0e4eff04ea963128a41faaef21f987272e05a2
-
httpd.apache.org
/security/vulnerabilities_24.html
patch, vendor-advisory
-
access.redhat.com
/errata/RHSA-2016:1420
vendor-advisory
-
security.gentoo.org
/glsa/201610-02
vendor-advisory
-
seclists.org
/fulldisclosure/2016/Jul/11
mailing-list
- oracle.com /technetwork/security-advisory/cpuoct2016-2881722.html
- apache.org /dist/httpd/CHANGES_2.4
-
securityfocus.com
/bid/91566
vdb-entry
- oracle.com /technetwork/topics/security/bulletinoct2016-3090566.html
-
securitytracker.com
/id/1036225
vdb-entry
-
openwall.com
/lists/oss-security/2016/07/05/5
mailing-list
- packetstormsecurity.com /files/137771/Apache-2.4.20-X509-Authentication-Bypass.html
- security.netapp.com /advisory/ntap-20180601-0001/
-
lists.apache.org
/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E
mailing-list
-
lists.apache.org
/thread.html/84a3714f0878781f6ed84473d1a503d2cc382277e100450209231830%40%3Ccvs.httpd.apache.org%3E
mailing-list
-
lists.apache.org
/thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E
mailing-list
-
lists.apache.org
/thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E
mailing-list
-
lists.apache.org
/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.apache.org%3E
mailing-list
-
lists.apache.org
/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E
mailing-list
-
lists.apache.org
/thread.html/re1e3a24664d35bcd0a0e793e0b5fc6ca6c107f99a1b2c545c5d4b467%40%3Ccvs.httpd.apache.org%3E
mailing-list
-
lists.apache.org
/thread.html/r04e89e873d54116a0635ef2f7061c15acc5ed27ef7500997beb65d6f%40%3Ccvs.httpd.apache.org%3E
mailing-list
-
lists.apache.org
/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E
mailing-list
-
lists.apache.org
/thread.html/rcc44594d4d6579b90deccd4536b5d31f099ef563df39b094be286b9e%40%3Ccvs.httpd.apache.org%3E
mailing-list
-
lists.apache.org
/thread.html/rb14daf9cc4e28d18cdc15d6a6ca74e565672fabf7ad89541071d008b%40%3Ccvs.httpd.apache.org%3E
mailing-list
-
lists.apache.org
/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E
mailing-list
Sources
- CVE List CVE-2016-4979
- NVD CVE-2016-4979
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.