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CVE-2016-4975

41
FAUCET Score

CVE-2016-4975 describes a CRLF injection vulnerability in Apache HTTP Server versions 2.4.1-2.4.23 and 2.2.0-2.2.31, specifically impacting sites utilizing mod_userdir. This flaw allows for HTTP response splitting attacks. Rated as Medium severity (CVSS 6.1), it requires user interaction and can lead to partial confidentiality and integrity compromise. While not in CISA's KEV catalog, exploit intelligence indicates a Nuclei template exists, and there is some community discussion and media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
2.2.0CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.2.0:*:*:*:*:*:*:*
2.2.2CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.2.2:*:*:*:*:*:*:*
2.2.3CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.2.3:*:*:*:*:*:*:*
2.2.4CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.2.4:*:*:*:*:*:*:*
2.2.6CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.2.6:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

6.1MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
2.7
CvssVersion
3.0

Exploit Intelligence

EPSS Score
19.80%
Probability of exploitation in next 30 days
EPSS Percentile
97.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
Nuclei: CVE-2016-4975 · Sep 30, 2021
This CVE's current EPSS score of 0.1980 is in the 99th percentile among its peer group of 26,219 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 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 (34)

apachepatch availablevia llm_extracted
Fixed in: 2.4
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-apache-commons-daemon-0:1.1.0-1.redhat_2.1.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-apache-commons-daemon-jsvc-1:1.1.0-1.redhat_2.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-apr-0:1.6.3-14.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-apr-util-0:1.6.1-9.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-httpd-0:2.4.29-17.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-mod_auth_kerb-0:5.4-36.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-mod_bmx-0:0.9.6-17.GA.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-mod_cluster-native-0:1.3.8-1.Final_redhat_2.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-mod_jk-0:1.2.43-1.redhat_1.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-mod_rt-0:2.4.1-19.GA.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-mod_security-0:2.9.1-23.GA.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-nghttp2-0:1.29.0-8.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-openssl-1:1.0.2n-11.jbcs.el6
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-apache-commons-daemon-0:1.1.0-1.redhat_2.1.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-apache-commons-daemon-jsvc-1:1.1.0-1.redhat_2.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-apr-0:1.6.3-14.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-httpd-0:2.4.29-17.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_auth_kerb-0:5.4-36.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_bmx-0:0.9.6-17.GA.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_cluster-native-0:1.3.8-1.Final_redhat_2.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_jk-0:1.2.43-1.redhat_1.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_rt-0:2.4.1-19.GA.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_security-0:2.9.1-23.GA.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-nghttp2-0:1.29.0-8.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-openssl-1:1.0.2n-11.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: Text-Only JBCS
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-apr-util-0:1.6.1-9.jbcs.el7
View patch
redhatno patchvia redhat_api
Product: Red Hat JBoss Enterprise Application Platform 6Fixed in: httpd
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 5Fixed in: httpd
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: httpd
redhatend of lifevia redhat_api
Product: Red Hat JBoss Enterprise Web Server 2Fixed in: httpd
redhatend of lifevia redhat_api
Product: Red Hat JBoss Web Server 3Fixed in: httpd

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-2016-4975Moderate

httpd: CRLF injection allowing HTTP response splitting attacks for sites which use mod_userdir

Aug 14, 2018
apachellm-apache-684e4d0003611bd4LOW

Apache HTTP Server 2.4 vulnerabilities - The Apache HTTP Server Project

References

httpd.apache.org / security/vulnerabilities_22.html
Vendor 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/8d63cb8e9100f28a99429b4328e4e7cebce861d5772ac9863ba2ae6f%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/f7f95ac1cd9895db2714fa3ebaa0b94d0c6df360f742a40951384a53%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/r04e89e873d54116a0635ef2f7061c15acc5ed27ef7500997beb65d6f%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/r57608dc51b79102f3952ae06f54d5277b649c86d6533dcd6a7d201f7%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/r75cbe9ea3e2114e4271bbeca7aff96117b50c1b6eb7c4772b0337c1f%40%3Ccvs.httpd.apache.org%3E
lists.apache.org / thread.html/r9ea3538f229874c80a10af473856a81fbf5f694cd7f471cc679ba70b%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/rdca61ae990660bacb682295f2a09d34612b7bb5f457577fe17f4d064%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
lists.apache.org / thread.html/rfbaf647d52c1cb843e726a0933f156366a806cead84fbd430951591b%40%3Ccvs.httpd.apache.org%3E
security.netapp.com / advisory/ntap-20180926-0006
Third Party Advisory
support.hpe.com / hpsc/doc/public/display
securityfocus.com / bid/105093
Third Party AdvisoryVDB Entry