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CVE-2016-2161

35
FAUCET Score

CVE-2016-2161 describes a denial-of-service vulnerability in Apache HTTP Server versions 2.4.0 to 2.4.23, where malicious input to mod_auth_digest can cause the server to crash repeatedly. This vulnerability is rated as High severity (CVSS 7.5), indicating it can be exploited remotely with low complexity to achieve a complete loss of availability. While there is no known active exploitation or public exploit code, the vulnerability has garnered some community discussion and media coverage, suggesting awareness within the security community.

Impacted Technologies

VendorProductVersion(s)CPE
2.4.0CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.4.0:*:*:*:*:*:*:*
2.4.1CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.4.1:*:*:*:*:*:*:*
2.4.2CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.4.2:*:*:*:*:*:*:*
2.4.3CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.4.3:*:*:*:*:*:*:*
2.4.6CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.4.6:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

7.5HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
20.95%
Probability of exploitation in next 30 days
EPSS Percentile
97.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.2095 is in the 96th percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (13)

apachepatch availablevia llm_extracted
Fixed in: 2.4
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-httpd-0:2.4.23-120.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-mod_security-0:2.9.1-19.GA.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-openssl-1:1.0.2h-13.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-httpd-0:2.4.23-120.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_security-0:2.9.1-19.GA.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-openssl-1:1.0.2h-13.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: httpd-0:2.4.6-45.el7_3.4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6Fixed in: httpd24-httpd-0:2.4.25-9.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 6.7 EUSFixed in: httpd24-httpd-0:2.4.25-9.el6
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: httpd24-httpd-0:2.4.25-9.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7.3 EUSFixed in: httpd24-httpd-0:2.4.25-9.el7
View patch
redhatpatch availablevia redhat_api
Product: Text-Only JBCS
View patch

Vendor Advisories (4)

apachellm-apache-f398f8ed28802aa3LOW

Apache HTTP Server 2.4 vulnerabilities - The Apache HTTP Server Project

Mar 2, 2026
apachellm-apache-a7a91ec4c0e9421dHIGH

Apache HTTP Server 2.4 vulnerabilities - The Apache HTTP Server Project

Dec 10, 2025
redhatCVE-2016-2161Moderate

httpd: DoS vulnerability in mod_auth_digest

Dec 20, 2016
apachellm-apache-684e4d0003611bd4LOW

Apache HTTP Server 2.4 vulnerabilities - The Apache HTTP Server Project

References

rhn.redhat.com / errata/RHSA-2017-1415.html
access.redhat.com / errata/RHSA-2017:0906
access.redhat.com / errata/RHSA-2017:1161
access.redhat.com / errata/RHSA-2017:1413
access.redhat.com / errata/RHSA-2017:1414
h20566.www2.hpe.com / hpsc/doc/public/display
Third Party Advisory
httpd.apache.org / security/vulnerabilities_24.html
Vendor Advisory
lists.apache.org / thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/84a3714f0878781f6ed84473d1a503d2cc382277e100450209231830%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/r04e89e873d54116a0635ef2f7061c15acc5ed27ef7500997beb65d6f%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/rb14daf9cc4e28d18cdc15d6a6ca74e565672fabf7ad89541071d008b%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/rcc44594d4d6579b90deccd4536b5d31f099ef563df39b094be286b9e%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/rd336919f655b7ff309385e34a143e41c503e133da80414485b3abcc9%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/re1e3a24664d35bcd0a0e793e0b5fc6ca6c107f99a1b2c545c5d4b467%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.apache.org%3E
security.gentoo.org / glsa/201701-36
Third Party Advisory
security.netapp.com / advisory/ntap-20180423-0001
support.apple.com / HT208221
tenable.com / security/tns-2017-04
debian.org / security/2017/dsa-3796
securityfocus.com / bid/95076
Third Party AdvisoryVDB Entry
securitytracker.com / id/1037508
Third Party AdvisoryVDB Entry