ZDF
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2017-9789

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 potent…

Published Jul 13, 2017 · catalog updated Jun 17, 2026 · http server

Last checked Nov 8, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2017-9789. EPSS is 9.51%. Act only if a listed version of http server is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
9.51%
Remediation
Advisory link
Affected products
cpe apache/http server

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe apache/http server2.4.26

How to fix CVE-2017-9789

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2017-9789. EPSS is 9.51%. Act only if a listed version of http server is installed.

Which versions are affected?

Compare what you have installed with apache/http server 2.4.26. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-416: Use After Free. EPSS 9.51%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Apache HTTP Server security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jul 13, 2017 · Monitored products — critical

    Detected

    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.

  2. Jun 17, 2026 · Monitored products — critical

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2017-9789

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2017-9789

    30-day exploitation probability 9.51%

    first.org
  • Monitored products — criticalVendor advisoryCVE-2017-9789

    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.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 8, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 8, 2026
  • CVE.orgNov 4, 2026
  • Monitored products — criticalNov 4, 2026