Apache HTTP Server up to 2.2.34/2.4.27 Limit Directive ap_limit_section HTTP Request use after free

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.3	$0-$5k	0.00

Summaryinfo

A vulnerability classified as problematic has been found in Apache HTTP Server up to 2.2.34/2.4.27. Affected by this vulnerability is the function ap_limit_section of the component Limit Directive. This manipulation as part of HTTP Request causes use after free. This vulnerability is tracked as CVE-2017-9798. The attack is possible to be carried out remotely. Moreover, an exploit is present. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Apache HTTP Server up to 2.2.34/2.4.27 (Web Server). Affected by this vulnerability is the function ap_limit_section of the component Limit Directive. The manipulation as part of a HTTP Request leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality. The summary by CVE is:

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.

The bug was discovered 09/18/2017. The weakness was disclosed 09/18/2017 (Website). The advisory is shared at exploit-db.com. This vulnerability is known as CVE-2017-9798 since 06/21/2017. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details and also a public exploit are known.

A public exploit has been developed by Hanno Bock and been published immediately after the advisory. It is possible to download the exploit at exploit-db.com. It is declared as highly functional. We expect the 0-day to have been worth approximately $5k-$25k. The vulnerability scanner Nessus provides a plugin with the ID 103309 (Amazon Linux AMI : httpd24 / httpd (ALAS-2017-896) (Optionsbleed)), which helps to determine the existence of the flaw in a target environment. It is assigned to the family Amazon Linux Local Security Checks and running in the context l. The commercial vulnerability scanner Qualys is able to test this issue with plugin 370677 (Apple macOS High Sierra 10.13.2, Security Update 2017-002 Sierra, and Security Update 2017-005 El Capitan Not Installed).

Upgrading eliminates this vulnerability. A possible mitigation has been published immediately after the disclosure of the vulnerability.

The vulnerability is also documented in the databases at Exploit-DB (42745), Tenable (103309) and SecurityFocus (BID 100872†). The entries VDB-92314, VDB-92773, VDB-92782 and VDB-92786 are pretty similar. Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Web Server

Vendor

• Apache

Name

• HTTP Server

Version

• 2.2.0
• 2.2.1
• 2.2.2
• 2.2.3
• 2.2.4
• 2.2.5
• 2.2.6
• 2.2.7
• 2.2.8
• 2.2.9
• 2.2.10
• 2.2.11
• 2.2.12
• 2.2.13
• 2.2.14
• 2.2.15
• 2.2.16
• 2.2.17
• 2.2.18
• 2.2.19
• 2.2.20
• 2.2.21
• 2.2.22
• 2.2.23
• 2.2.24
• 2.2.25
• 2.2.26
• 2.2.27
• 2.2.28
• 2.2.29
• 2.2.30
• 2.2.31
• 2.2.32
• 2.2.33
• 2.2.34
• 2.4.0
• 2.4.1
• 2.4.2
• 2.4.3
• 2.4.4
• 2.4.5
• 2.4.6
• 2.4.7
• 2.4.8
• 2.4.9
• 2.4.10
• 2.4.11
• 2.4.12
• 2.4.13
• 2.4.14
• 2.4.15
• 2.4.16
• 2.4.17
• 2.4.18
• 2.4.19
• 2.4.20
• 2.4.21
• 2.4.22
• 2.4.23
• 2.4.24
• 2.4.25
• 2.4.26
• 2.4.27

License

• open-source

Website

• Vendor: https://www.apache.org/

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔍
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

NVD Base Score: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Access: Public
Status: Highly functional
Author: Hanno Bock
Download: 🔍

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 103309
Nessus Name: Amazon Linux AMI : httpd24 / httpd (ALAS-2017-896) (Optionsbleed)
Nessus File: 🔍
Nessus Risk: 🔍
Nessus Family: 🔍
Nessus Context: 🔍

OpenVAS ID: 53754
OpenVAS Name: Debian Security Advisory DSA 3980-1 (apache2 - security update)
OpenVAS File: 🔍
OpenVAS Family: 🔍

Qualys ID: 🔍
Qualys Name: 🔍

MetaSploit ID: apache_optionsbleed.rb
MetaSploit Name: Apache ActiveMQ Directory Traversal
MetaSploit File: 🔍

Exploit-DB: 🔍

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

Reaction Time: 🔍
0-Day Time: 🔍
Exposure Time: 🔍
Exploit Delay Time: 🔍

Patch: github.com
Suricata ID: 2024759
Suricata Class: 🔍
Suricata Message: 🔍

Timelineinfo

06/21/2017 🔍
09/18/2017 +89 days 🔍
09/18/2017 +0 days 🔍
09/18/2017 +0 days 🔍
09/18/2017 +0 days 🔍
09/18/2017 +0 days 🔍
09/18/2017 +0 days 🔍
09/18/2017 +0 days 🔍
09/18/2017 +0 days 🔍
09/19/2017 +1 days 🔍
11/04/2025 +2968 days 🔍

Sourcesinfo

Vendor: apache.org

Advisory: RHSA-2017:2882
Researcher: Hanno Böck
Status: Confirmed
Confirmation: 🔍

CVE: CVE-2017-9798 (🔍)
GCVE (CVE): GCVE-0-2017-9798
GCVE (VulDB): GCVE-100-106777

OVAL: 🔍

SecurityFocus: 100872 - Apache HTTP Server CVE-2017-9798 Information Disclosure Vulnerability
SecurityTracker: 1039387

scip Labs: https://www.scip.ch/en/?labs.20161013
See also: 🔍

Entryinfo

Created: 09/18/2017 20:54
Updated: 11/04/2025 17:38
Changes: 09/18/2017 20:54 (89), 11/19/2019 08:28 (6), 01/13/2021 12:01 (3), 01/13/2021 12:04 (1), 12/29/2022 11:50 (4), 01/02/2025 04:52 (14), 11/04/2025 17:38 (1)
Complete: 🔍
Cache ID: 216:F34:103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

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