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CVE-2016-8740

75
FAUCET Score

CVE-2016-8740 describes a denial-of-service vulnerability in the mod_http2 module of Apache HTTP Server versions 2.4.17 through 2.4.23. This flaw allows remote attackers to exhaust server memory by sending crafted HTTP/2 CONTINUATION frames when h2 or h2c protocols are enabled. With a CVSS score of 7.5 (High), this vulnerability is easily exploitable over the network with low attack complexity, leading to a high impact on availability. While not listed in CISA's KEV catalog, an exploit is publicly available on ExploitDB, and it has garnered significant community discussion and media coverage, indicating its relevance despite being an older CVE.

Impacted Technologies

VendorProductVersion(s)CPE
2.4.17CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.4.17:*:*:*:*:*:*:*
2.4.18CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.4.18:*:*:*:*:*:*:*
2.4.19CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.4.19:*:*:*:*:*:*:*
2.4.20CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.4.20:*:*:*:*:*:*:*
2.4.21CPE matchmatch criteria
cpe:2.3:a:apache:http_server:2.4.21:*:*:*:*:*:*:*

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
79.07%
Probability of exploitation in next 30 days
EPSS Percentile
99.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
ExploitDB: EDB-40909 · Dec 12, 2016
This CVE's current EPSS score of 0.7907 is in the 99th 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
github_advisorypatch availablevia nvd_reference
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 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
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 6Fixed in: jbcs-httpd24-httpd-0:2.4.23-120.jbcs.el6
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-2016-8740Low

httpd: Incomplete handling of LimitRequestFields directive in mod_http2

Dec 4, 2016
apachellm-apache-684e4d0003611bd4LOW

Apache HTTP Server 2.4 vulnerabilities - The Apache HTTP Server Project

References

packetstormsecurity.com / files/140023/Apache-HTTPD-Web-Server-2.4.23-Memory-Exhaustion.html
ExploitThird Party AdvisoryVDB Entry
rhn.redhat.com / errata/RHSA-2017-1415.html
access.redhat.com / errata/RHSA-2017:1161
access.redhat.com / errata/RHSA-2017:1413
access.redhat.com / errata/RHSA-2017:1414
github.com / apache/httpd/commit/29c63b786ae028d82405421585e91283c8fa0da3
Issue TrackingPatchThird Party Advisory
h20566.www2.hpe.com / hpsc/doc/public/display
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/r476d175be0aaf4a17680ef98c5153b4d336eaef76fb2224cc94c463a%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
security.netapp.com / advisory/ntap-20180423-0001
support.apple.com / HT208221
exploit-db.com / exploits/40909
ExploitThird Party AdvisoryVDB Entry
tenable.com / security/tns-2017-04
securityfocus.com / bid/94650
Third Party AdvisoryVDB Entry
securitytracker.com / id/1037388
Third Party AdvisoryVDB Entry