CVE-2017-9788

CVE-2017-9788 is a critical-severity vulnerability in Apache Http Server with a CVSS 3.x base score of 9.1. Its EPSS exploit-prediction score of 57% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-20.

Key facts

Description

In Apache httpd before 2.2.34 and 2.4.x before 2.4.27, the value placeholder in [Proxy-]Authorization headers of type 'Digest' was not initialized or reset before or between successive key=value assignments by mod_auth_digest. Providing an initial key with no '=' assignment could reflect the stale value of uninitialized pool memory used by the prior request, leading to leakage of potentially confidential information, and a segfault in other cases resulting in denial of service.

Frequently asked questions

What is CVE-2017-9788?
In Apache httpd before 2.2.34 and 2.4.x before 2.4.27, the value placeholder in [Proxy-]Authorization headers of type 'Digest' was not initialized or reset before or between successive key=value assignments by mod_auth_digest. Providing an initial key with no '=' assignment could reflect the stale value of uninitialized pool memory used by the prior request, leading to leakage of potentially confidential information, and a segfault in other cases resulting in denial of service.
How severe is CVE-2017-9788?
CVE-2017-9788 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability high.
Is CVE-2017-9788 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 57% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2017-9788?
CVE-2017-9788 primarily affects Apache Http Server. In total, 31 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2017-9788?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2017-9788 published?
CVE-2017-9788 was published on 2017-07-13 and last updated on 2026-06-17.

References

Affected products (31)

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Threat intelligence

Threat-intel indicators referencing this CVE: