How severe is CVE-2017-9789?

CVE-2017-9789 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2017-9789 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2017-9789?

CVE-2017-9789 affects Apache Http Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2017-9789?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2017-9789 published?

CVE-2017-9789 was published on 2017-07-13 and last updated on 2026-06-17.

CVE-2017-9789

CVE-2017-9789 is a high-severity vulnerability in Apache Http Server with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-416.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 10% (95th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-416
Affected product: Apache Http Server
Published: 2017-07-13
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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 potentially erratic behaviour.
How severe is CVE-2017-9789?: CVE-2017-9789 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2017-9789 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2017-9789?: CVE-2017-9789 affects Apache Http Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2017-9789?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2017-9789 published?: CVE-2017-9789 was published on 2017-07-13 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:apache:http_server:2.4.26:*:*:*:*:*:*:*

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