// For flags

CVE-2016-4979

httpd: X509 client certificate authentication bypass using HTTP/2

Severity Score

7.5
*CVSS v3

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

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.

El servidor HTTP Apache 2.4.18 hasta la versión 2.4.20, cuando mod_http2 y mod_ssl están activados, no reconoce adecuadamente la directiva "SSLVerifyClient require" para autorización de petición HTTP/2, lo que permite a atacantes remotos eludir las restricciones destinadas al acceso aprovechando la capacidad de enviar múltiples peticiones sobre una sola conexión y abortar una renegociación.

A flaw was found in the way httpd performed client authentication using X.509 client certificates. When the HTTP/2 protocol was enabled, a remote attacker could use this flaw to access resources protected by certificate authentication without providing a valid client certificate.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Attack Vector
Network
Attack Complexity
Low
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
None
Attack Vector
Network
Attack Complexity
Medium
Authentication
None
Confidentiality
Partial
Integrity
Partial
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2016-05-24 CVE Reserved
  • 2016-07-05 CVE Published
  • 2023-03-07 EPSS Updated
  • 2024-08-06 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-284: Improper Access Control
  • CWE-287: Improper Authentication
CAPEC
References (27)
URL Tag Source
http://packetstormsecurity.com/files/137771/Apache-2.4.20-X509-Authentication-Bypass.html X_refsource_misc
http://seclists.org/fulldisclosure/2016/Jul/11 Mailing List
http://www.apache.org/dist/httpd/CHANGES_2.4 X_refsource_confirm
http://www.openwall.com/lists/oss-security/2016/07/05/5 Mailing List
http://www.oracle.com/technetwork/security-advisory/cpuoct2016-2881722.html X_refsource_confirm
http://www.oracle.com/technetwork/topics/security/bulletinoct2016-3090566.html X_refsource_confirm
http://www.securityfocus.com/bid/91566 Vdb Entry
http://www.securitytracker.com/id/1036225 Vdb Entry
https://github.com/apache/httpd/commit/2d0e4eff04ea963128a41faaef21f987272e05a2 X_refsource_confirm
https://lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E Mailing List
https://lists.apache.org/thread.html/84a3714f0878781f6ed84473d1a503d2cc382277e100450209231830%40%3Ccvs.httpd.apache.org%3E Mailing List
https://lists.apache.org/thread.html/r04e89e873d54116a0635ef2f7061c15acc5ed27ef7500997beb65d6f%40%3Ccvs.httpd.apache.org%3E Mailing List
https://lists.apache.org/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E Mailing List
https://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E Mailing List
https://lists.apache.org/thread.html/rb14daf9cc4e28d18cdc15d6a6ca74e565672fabf7ad89541071d008b%40%3Ccvs.httpd.apache.org%3E Mailing List
https://lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E Mailing List
https://lists.apache.org/thread.html/rcc44594d4d6579b90deccd4536b5d31f099ef563df39b094be286b9e%40%3Ccvs.httpd.apache.org%3E Mailing List
https://lists.apache.org/thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E Mailing List
https://lists.apache.org/thread.html/re1e3a24664d35bcd0a0e793e0b5fc6ca6c107f99a1b2c545c5d4b467%40%3Ccvs.httpd.apache.org%3E Mailing List
https://lists.apache.org/thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E Mailing List
https://lists.apache.org/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.apache.org%3E Mailing List
https://security.netapp.com/advisory/ntap-20180601-0001 X_refsource_confirm
URL Date SRC
URL Date SRC
http://httpd.apache.org/security/vulnerabilities_24.html 2023-11-07
URL Date SRC
https://access.redhat.com/errata/RHSA-2016:1420 2023-11-07
https://security.gentoo.org/glsa/201610-02 2023-11-07
https://access.redhat.com/security/cve/CVE-2016-4979 2016-07-18
https://bugzilla.redhat.com/show_bug.cgi?id=1352476 2016-07-18
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Apache
Search vendor "Apache"
 Http Server
Search vendor "Apache" for product "Http Server"
 2.4.18
Search vendor "Apache" for product "Http Server" and version "2.4.18"
-
Affected
Apache
Search vendor "Apache"
 Http Server
Search vendor "Apache" for product "Http Server"
 2.4.19
Search vendor "Apache" for product "Http Server" and version "2.4.19"
-
Affected
Apache
Search vendor "Apache"
 Http Server
Search vendor "Apache" for product "Http Server"
 2.4.20
Search vendor "Apache" for product "Http Server" and version "2.4.20"
-
Affected