Bug 1401528 (CVE-2016-8740)

Summary: CVE-2016-8740 httpd: Incomplete handling of LimitRequestFields directive in mod_http2
Product: [Other] Security Response Reporter: Adam Mariš <amaris>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: bbaranow, bmaxwell, cdewolf, csutherl, dandread, darran.lofthouse, dmoppert, dosoudil, fnasser, gzaronik, hhorak, huwang, jason.greene, jawilson, jboss-set, jclere, jdoyle, jkaluza, jorton, lgao, luhliari, mbabacek, mturk, myarboro, pahan, pgier, psakar, pslavice, rmeggins, rnetuka, rsvoboda, sardella, twalsh, vtunka, weli
Target Milestone: ---Keywords: Reopened, Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: httpd 2.4.24 Doc Type: If docs needed, set a value
Doc Text:
A vulnerability was found in httpd's handling of the LimitRequestFields directive in mod_http2, affecting servers with HTTP/2 enabled. An attacker could send crafted requests with headers larger than the server's available memory, causing httpd to crash.
 Story Points: ---
Clone Of: Environment:
Last Closed: 2017-04-26 14:06:47 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1401530, 1425463    
Bug Blocks: 1401531, 1406828, 1457678    
Attachments:
Description Flags
httpd 2.4.23 patch none

Description Adam Mariš 2016-12-05 14:06:56 UTC 
The HTTP/2 protocol implementation (mod_http2) had an incomplete handling of the LimitRequestFields directive. This allowed an attacker to inject unlimited request headers into the server, leading to eventual memory exhaustion.

Affects all versions from  2.4.17 to  2.4.23.

Mitigation:

As a temporary workaround - HTTP/2 can be disabled by changing
the configuration by removing h2 and h2c from the Protocols
line(s) in the configuration file. 

The resulting line should read:

		Protocols http/1.1

External References:

https://httpd.apache.org/security/vulnerabilities_24.html
http://seclists.org/bugtraq/2016/Dec/3
Comment 2 Adam Mariš 2016-12-05 14:10:43 UTC 
Created httpd tracking bugs for this issue:

Affects: fedora-all [bug 1401530]
Comment 3 Adam Mariš 2016-12-05 14:13:57 UTC 
Created attachment 1228070 [details]
httpd 2.4.23 patch
Comment 4 Doran Moppert 2016-12-16 04:16:01 UTC 
This doesn't affect default configurations, the impact is limited to a crash and there is amplification - ie, the attacker needs to send O(total available memory) bytes to cause a crash.
Comment 5 Doran Moppert 2016-12-16 04:17:57 UTC 
Statement:

Red Hat Product Security has rated this issue as having Low security
impact. This issue is not currently planned to be addressed in future
updates. For additional information, refer to the Issue Severity
Classification: https://access.redhat.com/security/updates/classification/.
Comment 10 errata-xmlrpc 2017-04-26 10:22:33 UTC 
This issue has been addressed in the following products:

  Red Hat Software Collections for Red Hat Enterprise Linux 6
  Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUS
  Red Hat Software Collections for Red Hat Enterprise Linux 7
  Red Hat Software Collections for Red Hat Enterprise Linux 7.3 EUS

Via RHSA-2017:1161 https://access.redhat.com/errata/RHSA-2017:1161
Comment 11 errata-xmlrpc 2017-06-07 17:44:45 UTC 
This issue has been addressed in the following products:

  Red Hat JBoss Core Services

Via RHSA-2017:1415 https://access.redhat.com/errata/RHSA-2017:1415
Comment 12 errata-xmlrpc 2017-06-07 17:56:26 UTC 
This issue has been addressed in the following products:

  JBoss Core Services on RHEL 6

Via RHSA-2017:1414 https://access.redhat.com/errata/RHSA-2017:1414
Comment 13 errata-xmlrpc 2017-06-07 17:59:10 UTC 
This issue has been addressed in the following products:

  JBoss Core Services on RHEL 7

Via RHSA-2017:1413 https://access.redhat.com/errata/RHSA-2017:1413