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Fencer Intel
medium 5.9

CVE-2016-1546 json

The Apache HTTP Server 2.4.17 and 2.4.18, when mod_http2 is enabled, does not limit the number of simultaneous stream workers for a single…

published 2016-07-06 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-2641

cvss
5.9
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
15.9%
EPSS 15.9% chance of exploitation in 30 days, percentile 96%
public exploits
0
none known

Summary

The Apache HTTP Server 2.4.17 and 2.4.18, when mod_http2 is enabled, does not limit the number of simultaneous stream workers for a single HTTP/2 connection, which allows remote attackers to cause a denial of service (stream-processing outage) via modified flow-control windows.

Patch / fix

  • apache2 Debian 14, Debian 13, Debian 12 2.4.20-1

debian advisories DEBIAN-CVE-2016-1546

  • httpd24-httpd RHEL 2 SOFTWARE_COLLECTIONS 2.4.25-9.el6
  • httpd24-httpd RHEL 2 SOFTWARE_COLLECTIONS 2.4.25-9.el7
  • httpd24-mod_ssl RHEL 2 SOFTWARE_COLLECTIONS 1:2.4.25-9.el6
  • httpd24-mod_ssl RHEL 2 SOFTWARE_COLLECTIONS 1:2.4.25-9.el7
  • httpd24-mod_ldap RHEL 2 SOFTWARE_COLLECTIONS 2.4.25-9.el6
  • httpd24-mod_ldap RHEL 2 SOFTWARE_COLLECTIONS 2.4.25-9.el7
  • httpd24-httpd-tools RHEL 2 SOFTWARE_COLLECTIONS 2.4.25-9.el6
  • httpd24-httpd-tools RHEL 2 SOFTWARE_COLLECTIONS 2.4.25-9.el7

red hat advisories RHSA-2017:1161

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-1546 updated cvss 4.3

httpd: mod_http2 denial-of-service by thread starvation

  • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 6) httpd24-httpd 2.4.25-9.el6, httpd24-mod_ssl 2.4.25-9.el6, httpd24-mod_ldap 2.4.25-9.el6, httpd24-httpd-tools 2.4.25-9.el6, httpd24-mod_session 2.4.25-9.el6, httpd24-httpd-manual 2.4.25-9.el6, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) httpd24-httpd 2.4.25-9.el7, httpd24-mod_ssl 2.4.25-9.el7, httpd24-mod_ldap 2.4.25-9.el7, httpd24-httpd-tools 2.4.25-9.el7, httpd24-mod_session 2.4.25-9.el7, httpd24-httpd-manual 2.4.25-9.el7, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 6.7) httpd24-httpd 2.4.25-9.el6, httpd24-mod_ssl 2.4.25-9.el6, httpd24-mod_ldap 2.4.25-9.el6, httpd24-httpd-tools 2.4.25-9.el6, httpd24-mod_session 2.4.25-9.el6, httpd24-httpd-manual 2.4.25-9.el6, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.3) httpd24-httpd 2.4.25-9.el7, httpd24-mod_ssl 2.4.25-9.el7, httpd24-mod_ldap 2.4.25-9.el7, httpd24-httpd-tools 2.4.25-9.el7, httpd24-mod_session 2.4.25-9.el7, httpd24-httpd-manual 2.4.25-9.el7, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 6) httpd24-httpd 2.4.25-9.el6, httpd24-mod_ssl 2.4.25-9.el6, httpd24-mod_ldap 2.4.25-9.el6, httpd24-httpd-tools 2.4.25-9.el6, httpd24-mod_session 2.4.25-9.el6, httpd24-httpd-manual 2.4.25-9.el6, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) httpd24-httpd 2.4.25-9.el7, httpd24-mod_ssl 2.4.25-9.el7, httpd24-mod_ldap 2.4.25-9.el7, httpd24-httpd-tools 2.4.25-9.el7, httpd24-mod_session 2.4.25-9.el7, httpd24-httpd-manual 2.4.25-9.el7, +1 more
    fixed: vendor fix RHSA-2017:1161
  • Red Hat CloudForms Management Engine 5 httpd Red Hat Directory Server 8 httpd Red Hat Enterprise Linux 5 httpd Red Hat Enterprise Linux 6 httpd, mod_ssl, httpd-tools, httpd-manual Red Hat Enterprise Linux 7 httpd, mod_ssl, mod_ldap, httpd-tools, mod_session, httpd-manual, +1 more Red Hat JBoss Enterprise Application Platform 5 httpd
    +4 more products
    Red Hat JBoss Enterprise Application Platform 6 httpd, mod_ssl, mod_ldap, httpd-tools, httpd-manual Red Hat JBoss Enterprise Web Server 1 httpd Red Hat JBoss Enterprise Web Server 2 jbcs-httpd24, jbcs-httpd24-runtime Red Hat JBoss Enterprise Web Server 3 httpd
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

15.92% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 5.9 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P

Classification

Weakness
  • CWE-399 Resource Management Errors
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.