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Fencer Intel
high 7.5

CVE-2017-9789 json

When under stress, closing many connections, the HTTP/2 handling code in Apache httpd 2.4.26 would sometimes access memory after it has bee…

published 2017-07-13 9 y ago modified 2026-06-17 4 mo ago also EUVD-2017-18717

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
9.5%
EPSS 9.5% chance of exploitation in 30 days, percentile 95%
public exploits
0
none known

Summary

When under stress, closing many connections, the HTTP/2 handling code in Apache httpd 2.4.26 would sometimes access memory after it has been freed, resulting in potentially erratic behaviour.

Patch / fix

  • apache2 SLES for SAP 12 SP3, SLES for SAP 12 SP2, SLES for Raspberry Pi 12 SP2 +4 more 2.4.23-29.13.1

suse advisories SUSE-SU-2018:0261-1

  • apache2 Alpine 3.6, Alpine 3.5, Alpine 3.4 +1 more 2.4.27-r0

alpine advisories ALPINE-CVE-2017-9789

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • apache Arch Linux 2.4.27-1

arch linux advisories AVG-350

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-2017-9789 updated cvss 6.5

httpd: Read after free in mod_http2

  • 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 Core Services jbcs-httpd24-httpd Red Hat JBoss Enterprise Application Platform 5 httpd Red Hat JBoss Enterprise Application Platform 6 httpd, mod_ssl, mod_ldap, httpd-tools, httpd-manual
    +4 more products
    Red Hat JBoss Enterprise Web Server 1 httpd Red Hat JBoss Enterprise Web Server 2 jbcs-httpd24, jbcs-httpd24-runtime Red Hat JBoss Web Server 3 httpd24 Red Hat Software Collections httpd24-httpd, httpd24-mod_md, httpd24-mod_ssl, httpd24-mod_ldap, httpd24-httpd-tools, httpd24-mod_session, +2 more
    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

9.51% chance of exploitation in the next 30 days, higher than 95% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

  • Apache Software Foundation Apache HTTP Server

Classification

Weakness
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.