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    CVE-2016-8740

    The mod_http2 module in the Apache HTTP Server 2.4.17 through 2.4.23, when the Protocols configuration includes h2 or h2c, does not restrict request-header length, which allows remote attackers to cause a denial of service (memory consumption) via crafted CONTINUATION frames in an HTTP/2 request.

    Published:Dec 4, 2016
    Last Modified:Apr 12, 2025
    EPS:Dec 5, 2016
    EPSS Score:0.62627
    CVSS Score:7.5

    Affected Products

    Vendor
    Apache
    Product
    Http Server
    Vendor
    Redhat
    Product
    Jboss Core Services
    Vendor
    Redhat
    Product
    Rhel Software Collections

    Exploits

    http://packetstormsecurity.com/files/140023/Apache-HTTPD-Web-Server-2.4.23-Memory-Exhaustion.htmlhttps://www.exploit-db.com/exploits/40909/http://packetstormsecurity.com/files/140023/Apache-HTTPD-Web-Server-2.4.23-Memory-Exhaustion.htmlhttps://www.exploit-db.com/exploits/40909/https://www.exploit-db.com/exploits/40909https://github.com/jptr218/apachedoshttps://github.com/lcfpadilha/mac0352-ep4

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-10 Buffer Overflow via Environment Variables
    CAPEC-101 Server Side Include (SSI) Injection
    CAPEC-104 Cross Zone Scripting
    CAPEC-108 Command Line Execution through SQL Injection
    CAPEC-109 Object Relational Mapping Injection
    CAPEC-110 SQL Injection through SOAP Parameter Tampering
    CAPEC-120 Double Encoding
    CAPEC-125 Flooding
    CAPEC-13 Subverting Environment Variable Values
    CAPEC-130 Excessive Allocation
    CAPEC-135 Format String Injection
    CAPEC-136 LDAP Injection
    CAPEC-14 Client-side Injection-induced Buffer Overflow
    CAPEC-147 XML Ping of the Death
    CAPEC-153 Input Data Manipulation
    CAPEC-182 Flash Injection
    CAPEC-197 Exponential Data Expansion
    CAPEC-209 XSS Using MIME Type Mismatch
    CAPEC-22 Exploiting Trust in Client
    CAPEC-229 Serialized Data Parameter Blowup
    CAPEC-23 File Content Injection
    CAPEC-230 Serialized Data with Nested Payloads
    CAPEC-231 Oversized Serialized Data Payloads
    CAPEC-24 Filter Failure through Buffer Overflow
    CAPEC-250 XML Injection
    CAPEC-261 Fuzzing for garnering other adjacent user/sensitive data
    CAPEC-267 Leverage Alternate Encoding
    CAPEC-28 Fuzzing
    CAPEC-3 Using Leading 'Ghost' Character Sequences to Bypass Input Filters
    CAPEC-31 Accessing/Intercepting/Modifying HTTP Cookies
    CAPEC-42 MIME Conversion
    CAPEC-43 Exploiting Multiple Input Interpretation Layers
    CAPEC-45 Buffer Overflow via Symbolic Links
    CAPEC-46 Overflow Variables and Tags
    CAPEC-469 HTTP DoS
    CAPEC-47 Buffer Overflow via Parameter Expansion
    CAPEC-473 Signature Spoof
    CAPEC-482 TCP Flood
    CAPEC-486 UDP Flood
    CAPEC-487 ICMP Flood
    CAPEC-488 HTTP Flood
    CAPEC-489 SSL Flood
    CAPEC-490 Amplification
    CAPEC-491 Quadratic Data Expansion
    CAPEC-493 SOAP Array Blowup
    CAPEC-494 TCP Fragmentation
    CAPEC-495 UDP Fragmentation
    CAPEC-496 ICMP Fragmentation
    CAPEC-52 Embedding NULL Bytes
    CAPEC-528 XML Flood
    CAPEC-53 Postfix, Null Terminate, and Backslash
    CAPEC-588 DOM-Based XSS
    CAPEC-63 Cross-Site Scripting (XSS)
    CAPEC-64 Using Slashes and URL Encoding Combined to Bypass Validation Logic
    CAPEC-664 Server Side Request Forgery
    CAPEC-67 String Format Overflow in syslog()
    CAPEC-7 Blind SQL Injection
    CAPEC-71 Using Unicode Encoding to Bypass Validation Logic
    CAPEC-72 URL Encoding
    CAPEC-73 User-Controlled Filename
    CAPEC-78 Using Escaped Slashes in Alternate Encoding
    CAPEC-79 Using Slashes in Alternate Encoding
    CAPEC-8 Buffer Overflow in an API Call
    CAPEC-80 Using UTF-8 Encoding to Bypass Validation Logic
    CAPEC-81 Web Server Logs Tampering
    CAPEC-83 XPath Injection
    CAPEC-85 AJAX Footprinting
    CAPEC-88 OS Command Injection
    CAPEC-9 Buffer Overflow in Local Command-Line Utilities

    Related CVEs

    CVE-2026-48913 (CVSS 7.3) — Use After Free vulnerability in Apache HTTP Server module mod_http2 when file handles are already exhausted. …
    CVE-2026-42536 (CVSS 7.5) — Heap-based Buffer Overflow vulnerability in Apache HTTP Server with mod_xml2enc, xml2StartParse, and untrusted…
    CVE-2026-44185 (CVSS 7.3) — Buffer Over-read vulnerability in Apache HTTP Server via outbound OCSP requests to an attacker controlled OCSP…
    CVE-2026-34355 (CVSS 7.5) — A buffer overflow in mod_proxy_html in Apache HTTP Server 2.4.67 and earlier allows an attack by an untrusted …
    CVE-2026-44631 (CVSS 9.8) — Buffer Underwrite vulnerability in Apache HTTP Server on crafted regular expressions in the configuration. Th…
    CVE-2026-44119 (CVSS 5.5) — Improper Privilege Management vulnerability in Apache HTTP Server 2.4.67 and earlier allows local .htaccess au…
    CVE-2026-43951 (CVSS 6.5) — Out-of-bounds Read vulnerability in Apache HTTP Server with mod_headers and mod_mime and multiple response lan…
    CVE-2026-42535 (CVSS 9.1) — A path handling issue in mod_dav_fs in Apache 2.4.67 and earlier allows a WebDAV content author to directly ma…
    CVE-2026-34356 (CVSS 7.5) — Heap-based Buffer Overflow vulnerability in Apache HTTP Server with malicious backend servers and ProxyPassRev…
    CVE-2026-44186 (CVSS 7.3) — Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in the mod_proxy_ftp module in Apache HTT…

    References

    http://packetstormsecurity.com/files/140023/Apache-HTTPD-Web-Server-2.4.23-Memory-Exhaustion.html
    http://rhn.redhat.com/errata/RHSA-2017-1415.html
    http://www.securityfocus.com/bid/94650
    http://www.securitytracker.com/id/1037388
    https://access.redhat.com/errata/RHSA-2017:1161
    https://access.redhat.com/errata/RHSA-2017:1413
    https://access.redhat.com/errata/RHSA-2017:1414
    https://github.com/apache/httpd/commit/29c63b786ae028d82405421585e91283c8fa0da3
    https://h20566.www2.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03725en_us
    https://lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/84a3714f0878781f6ed84473d1a503d2cc382277e100450209231830%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/r04e89e873d54116a0635ef2f7061c15acc5ed27ef7500997beb65d6f%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/r476d175be0aaf4a17680ef98c5153b4d336eaef76fb2224cc94c463a%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rb14daf9cc4e28d18cdc15d6a6ca74e565672fabf7ad89541071d008b%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rcc44594d4d6579b90deccd4536b5d31f099ef563df39b094be286b9e%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rd336919f655b7ff309385e34a143e41c503e133da80414485b3abcc9%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/re1e3a24664d35bcd0a0e793e0b5fc6ca6c107f99a1b2c545c5d4b467%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.apache.org%3E
    https://security.gentoo.org/glsa/201701-36
    https://security.netapp.com/advisory/ntap-20180423-0001/
    https://support.apple.com/HT208221
    https://www.exploit-db.com/exploits/40909/
    https://www.tenable.com/security/tns-2017-04
    http://packetstormsecurity.com/files/140023/Apache-HTTPD-Web-Server-2.4.23-Memory-Exhaustion.html
    http://rhn.redhat.com/errata/RHSA-2017-1415.html
    http://www.securityfocus.com/bid/94650
    http://www.securitytracker.com/id/1037388
    https://access.redhat.com/errata/RHSA-2017:1161
    https://access.redhat.com/errata/RHSA-2017:1413
    https://access.redhat.com/errata/RHSA-2017:1414
    https://github.com/apache/httpd/commit/29c63b786ae028d82405421585e91283c8fa0da3
    https://h20566.www2.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03725en_us
    https://lists.apache.org/thread.html/56c2e7cc9deb1c12a843d0dc251ea7fd3e7e80293cde02fcd65286ba%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/84a3714f0878781f6ed84473d1a503d2cc382277e100450209231830%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/r04e89e873d54116a0635ef2f7061c15acc5ed27ef7500997beb65d6f%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/r476d175be0aaf4a17680ef98c5153b4d336eaef76fb2224cc94c463a%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rb14daf9cc4e28d18cdc15d6a6ca74e565672fabf7ad89541071d008b%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rcc44594d4d6579b90deccd4536b5d31f099ef563df39b094be286b9e%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rd18c3c43602e66f9cdcf09f1de233804975b9572b0456cc582390b6f%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rd336919f655b7ff309385e34a143e41c503e133da80414485b3abcc9%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/re1e3a24664d35bcd0a0e793e0b5fc6ca6c107f99a1b2c545c5d4b467%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/re3d27b6250aa8548b8845d314bb8a350b3df326cacbbfdfe4d455234%40%3Ccvs.httpd.apache.org%3E
    https://lists.apache.org/thread.html/rf6449464fd8b7437704c55f88361b66f12d5b5f90bcce66af4be4ba9%40%3Ccvs.httpd.apache.org%3E
    https://security.gentoo.org/glsa/201701-36
    https://security.netapp.com/advisory/ntap-20180423-0001/
    https://support.apple.com/HT208221
    https://www.exploit-db.com/exploits/40909/
    https://www.tenable.com/security/tns-2017-04

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High