cbcvebase.
CVE-2018-11763
published 2018-09-25

CVE-2018-11763: In Apache HTTP Server 2.4.17 to 2.4.34, by sending continuous, large SETTINGS frames a client can occupy a connection, server thread and CPU time without any…

PriorityP275medium5.9CVSS 3.0
AVNACHPRNUINSUCNINAH
ITWVulnCheck KEV
Exploited in the wild
EPSS
51.00%
98.8th percentile
In Apache HTTP Server 2.4.17 to 2.4.34, by sending continuous, large SETTINGS frames a client can occupy a connection, server thread and CPU time without any connection timeout coming to effect. This affects only HTTP/2 connections. A possible mitigation is to not enable the h2 protocol.

Affected

19 ranges
VendorProductVersion rangeFixed in
apachehttp_server2.4.17 – 2.4.34
apachehttpd
apache_software_foundationapache_http_server
canonicalubuntu_linux
debianapache2< apache2 2.4.35-1 (bookworm)apache2 2.4.35-1 (bookworm)
oracleenterprise_manager_ops_center
oraclehospitality_guest_access
oraclehospitality_guest_access
oracleinstantis_enterprisetrack
oracleinstantis_enterprisetrack
oracleinstantis_enterprisetrack
oracleretail_xstore_point_of_service
oracleretail_xstore_point_of_service
oraclesecure_global_desktop
redhatenterprise_linux
redhatenterprise_linux
redhatenterprise_linux
redhatenterprise_linux
redhatenterprise_linux

Detection & IOCsextracted from sources · hover to see the quote

  • Attack targets only HTTP/2 (h2) connections; detection should focus on monitoring for continuous, large SETTINGS frames over HTTP/2 connections that never time out.
  • More specifically, the attack uses SETTINGS frames sent at maximum size continuously; look for HTTP/2 SETTINGS frame floods from a single client connection.
  • ·The vulnerability only affects servers with the h2 protocol enabled. Disabling h2 is a possible mitigation.
  • ·Affected Apache httpd versions are 2.4.17 through 2.4.34 (specifically: 2.4.18, 2.4.20, 2.4.23, 2.4.25, 2.4.26, 2.4.27, 2.4.28, 2.4.29, 2.4.30, 2.4.33, 2.4.34). Fixed in 2.4.35 and mod_http2 1.11.0 and later.
  • ·Red Hat Enterprise Linux 7 and earlier httpd packages do not include HTTP/2 support and are therefore not affected.

CVSS provenance

nvdv3.05.9MEDIUMCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
nvdv2.04.3MEDIUMAV:N/AC:M/Au:N/C:N/I:N/A:P
osv5.9MEDIUM
vulncheck5.9MEDIUM
vendor_apache5.9LOW
vendor_debian5.9MEDIUM
vendor_redhat5.9MEDIUM
vendor_ubuntu5.9MEDIUM
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