CVE & CISA-KEV Catalog

CVE-2017-9798

HIGHEPSS 100th pctl
7.5
CVSS v3
NVD

Description

Apache httpd allows remote attackers to read secret data from process memory if the Limit directive can be set in a user's .htaccess file, or if httpd.conf has certain misconfigurations, aka Optionsbleed. This affects the Apache HTTP Server through 2.2.34 and 2.4.x through 2.4.27. The attacker sends an unauthenticated OPTIONS HTTP request when attempting to read secret data. This is a use-after-free issue and thus secret data is not always sent, and the specific data depends on many factors including configuration. Exploitation with .htaccess can be blocked with a patch to the ap_limit_section function in server/core.c.

CWE-416Use After Free

How to fix

Remediation Available
apache2Debian
Fixed in:2.4.27-6CVE-2017-9798
Fixed in:2.4.27-6CVE-2017-9798
Fixed in:2.4.27-6CVE-2017-9798
Fixed in:2.4.27-6CVE-2017-9798
apache2Ubuntu
Fixed in:2.4.7-1ubuntu4.18USN-3425-1
Fixed in:2.4.18-2ubuntu3.5USN-3425-1
apache2-binUbuntu
Fixed in:2.4.7-1ubuntu4.18USN-3425-1
Fixed in:2.4.18-2ubuntu3.5USN-3425-1

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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityNone
AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Exploit Intelligence

95.00%probability of exploitation in 30 days
100thpercentile

Very high risk: more likely to be exploited than 100% of all known CVEs.

References

Exploit1
Vendor Advisory1
Mailing List1

Related Vulnerabilities

Other CWE-416 (Use After Free) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2019-0708Critical9.8100%KEV + Ransom-
CVE-2021-31166Critical9.8100%KEVFix
CVE-2015-5119Critical9.899%KEV-
CVE-2010-3962High8.196%KEV-
CVE-2015-0313Critical9.896%KEVFix
CVE-2021-34833High7.896%--

Common questions

How do I fix CVE-2017-9798?

Published advisories record a fix for 3 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2017-9798 being actively exploited?

Not that we know of. CVE-2017-9798 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 95.0% is the estimated probability that it will be exploited in the next 30 days. That is higher than 100% of all scored CVEs.

How severe is CVE-2017-9798?

CVE-2017-9798 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2017-9798 affect?

Published advisories record a fix for apache2 (Debian), apache2 (Ubuntu), apache2-bin (Ubuntu). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-13.