CVE-2021-26691

Apache HTTP Server mod_session response handling heap overflow

Severity Score

9.8

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

In Apache HTTP Server versions 2.4.0 to 2.4.46 a specially crafted SessionHeader sent by an origin server could cause a heap overflow

Apache HTTP Server versiones 2.4.0 a 2.4.46 , un parámetro SessionHeader especialmente diseñado enviado por un servidor de origen podría causar un desbordamiento de pila

A heap overflow flaw was found In Apache httpd mod_session. The highest threat from this vulnerability is to system availability.

Red Hat JBoss Core Services is a set of supplementary software for Red Hat JBoss middleware products. This software, such as Apache HTTP Server, is common to multiple JBoss middleware products, and is packaged under Red Hat JBoss Core Services to allow for faster distribution of updates, and for a more consistent update experience. This release adds the new Apache HTTP Server 2.4.37 Service Pack 10 packages that are part of the JBoss Core Services offering. This release serves as a replacement for Red Hat JBoss Core Services Apache HTTP Server 2.4.37 Service Pack 9 and includes bug fixes and enhancements. Issues addressed include buffer over-read, heap overflow, integer overflow, and null pointer vulnerabilities.

*Credits: Discovered internally Christophe Jaillet

CVSS Scores

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Network

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-02-04 CVE Reserved
2021-06-10 CVE Published
2024-08-03 CVE Updated
2025-05-29 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-122: Heap-based Buffer Overflow
CWE-787: Out-of-bounds Write

CAPEC

References (15)

URL	Tag	Source
http://www.openwall.com/lists/oss-security/2021/06/10/7	Mailing List
https://lists.apache.org/thread.html/r50cae1b71f1e7421069036b213c26da7d8f47dd59874e3bd956959fe%40%3Cannounce.httpd.apache.org%3E	Mailing List
https://lists.apache.org/thread.html/r7f2b70b621651548f4b6f027552f1dd91705d7111bb5d15cda0a68dd%40%3Cdev.httpd.apache.org%3E	Mailing List
https://lists.debian.org/debian-lts-announce/2021/07/msg00006.html	Mailing List
https://security.netapp.com/advisory/ntap-20210702-0001	Third Party Advisory

URL	Date	SRC

URL	Date	SRC
https://www.oracle.com/security-alerts/cpujan2022.html	2023-11-07
https://www.oracle.com/security-alerts/cpuoct2021.html	2023-11-07

URL	Date	SRC
http://httpd.apache.org/security/vulnerabilities_24.html	2023-11-07
https://lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3E	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R	2023-11-07
https://security.gentoo.org/glsa/202107-38	2023-11-07
https://www.debian.org/security/2021/dsa-4937	2023-11-07
https://access.redhat.com/security/cve/CVE-2021-26691	2022-01-17
https://bugzilla.redhat.com/show_bug.cgi?id=1966732	2022-01-17

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Apache Search vendor "Apache"		Http Server Search vendor "Apache" for product "Http Server"				>= 2.4.0 <= 2.4.46 Search vendor "Apache" for product "Http Server" and version " >= 2.4.0 <= 2.4.46"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				9.0 Search vendor "Debian" for product "Debian Linux" and version "9.0"		-		Affected
Debian Search vendor "Debian"		Debian Linux Search vendor "Debian" for product "Debian Linux"				10.0 Search vendor "Debian" for product "Debian Linux" and version "10.0"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				34 Search vendor "Fedoraproject" for product "Fedora" and version "34"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				35 Search vendor "Fedoraproject" for product "Fedora" and version "35"		-		Affected
Oracle Search vendor "Oracle"		Enterprise Manager Ops Center Search vendor "Oracle" for product "Enterprise Manager Ops Center"				12.4.0.0 Search vendor "Oracle" for product "Enterprise Manager Ops Center" and version "12.4.0.0"		-		Affected
Oracle Search vendor "Oracle"		Instantis Enterprisetrack Search vendor "Oracle" for product "Instantis Enterprisetrack"				17.1 Search vendor "Oracle" for product "Instantis Enterprisetrack" and version "17.1"		-		Affected
Oracle Search vendor "Oracle"		Instantis Enterprisetrack Search vendor "Oracle" for product "Instantis Enterprisetrack"				17.2 Search vendor "Oracle" for product "Instantis Enterprisetrack" and version "17.2"		-		Affected
Oracle Search vendor "Oracle"		Instantis Enterprisetrack Search vendor "Oracle" for product "Instantis Enterprisetrack"				17.3 Search vendor "Oracle" for product "Instantis Enterprisetrack" and version "17.3"		-		Affected
Oracle Search vendor "Oracle"		Secure Backup Search vendor "Oracle" for product "Secure Backup"				< 18.1.0.1.0 Search vendor "Oracle" for product "Secure Backup" and version " < 18.1.0.1.0"		-		Affected
Oracle Search vendor "Oracle"		Zfs Storage Appliance Kit Search vendor "Oracle" for product "Zfs Storage Appliance Kit"				8.8 Search vendor "Oracle" for product "Zfs Storage Appliance Kit" and version "8.8"		-		Affected
Netapp Search vendor "Netapp"		Cloud Backup Search vendor "Netapp" for product "Cloud Backup"				-		-		Affected