CVE-2021-26690
published 2021-06-10CVE-2021-26690: Apache HTTP Server versions 2.4.0 to 2.4.46 A specially crafted Cookie header handled by mod_session can cause a NULL pointer dereference and crash, leading to…
PriorityP355high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
65.07%
99.2th percentile
Apache HTTP Server versions 2.4.0 to 2.4.46 A specially crafted Cookie header handled by mod_session can cause a NULL pointer dereference and crash, leading to a possible Denial Of Service
Affected
42 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| apache | http_server | 2.4.0 – 2.4.46 | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
| apache_software_foundation | apache_http_server | — | — |
Detection & IOCsextracted from sources · hover to see the quote
- →The vulnerability is triggered by a specially crafted Cookie header sent to Apache httpd with mod_session enabled. Monitor for malformed or oversized Cookie headers targeting mod_session endpoints. ↗
- →The NULL pointer dereference occurs in the mod_session parser. Review Apache httpd crash logs (child process crashes) as an indicator of exploitation attempts. ↗
- →Reference the upstream patch commit for diff-based detection or integrity checking of the mod_session parser source/binary. ↗
- ·Only configurations using the 'SessionEnv' directive are vulnerable. This directive is not enabled in default httpd configurations, significantly limiting exposure. ↗
- ·Affected Apache HTTP Server versions are 2.4.0 through 2.4.46. Systems running 2.4.47+ (or patched 2.4.46 packages) are not vulnerable. ↗
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvdv2.05.0MEDIUMAV:N/AC:L/Au:N/C:N/I:N/A:P
osv7.5HIGH
vendor_debian7.5HIGH
vendor_msrc7.5HIGH
vendor_redhat7.5HIGH
vendor_ubuntu7.5HIGH
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Ubuntu
Apache HTTP Server vulnerabilities
vendor_ubuntu·2021-06-21·CVSS 7.5
CVE-2021-26691 [HIGH] Apache HTTP Server vulnerabilities
Title: Apache HTTP Server vulnerabilities
Summary: Several security issues were fixed in Apache HTTP Server.
Marc Stern discovered that the Apache mod_proxy_http module incorrectly
handled certain requests. A remote attacker could possibly use this issue
to cause Apache to crash, resulting in a denial of service. This issue only
affected Ubuntu 20.04 LTS, Ubuntu 20.10, and Ubuntu 21.04. (CVE-2020-13950)
Antonio Morales discovered that the Apache mod_auth_digest module
incorrectly handled certain Digest nonces. A remote attacker could possibly
use this issue to cause Apache to crash, resulting in a denial of service.
(CVE-2020-35452)
Antonio Morales discovered that the Apache mod_session module incorrectly
handled certain Cookie headers. A remote attacker could possibly use this
issue t
Ubuntu
Apache HTTP Server vulnerabilities
vendor_ubuntu·2021-06-21·CVSS 7.3
CVE-2021-26691 [HIGH] Apache HTTP Server vulnerabilities
Title: Apache HTTP Server vulnerabilities
Summary: Several security issues were fixed in Apache HTTP Server.
USN-4994-1 fixed several vulnerabilities in Apache. This update provides
the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.
Original advisory details:
Antonio Morales discovered that the Apache mod_auth_digest module
incorrectly handled certain Digest nonces. A remote attacker could possibly
use this issue to cause Apache to crash, resulting in a denial of service.
(CVE-2020-35452)
Antonio Morales discovered that the Apache mod_session module incorrectly
handled certain Cookie headers. A remote attacker could possibly use this
issue to cause Apache to crash, resulting in a denial of service.
(CVE-2021-26690)
Christophe Jaillet discovered that the Apache mod_se
Microsoft
mod_session NULL pointer dereference
vendor_msrc·2021-06-08·CVSS 7.5
CVE-2021-26690 [HIGH] CWE-476 mod_session NULL pointer dereference
mod_session NULL pointer dereference
FAQ: Is Azure Linux the only Microsoft product that includes this open-source library and is therefore potentially affected by this vulnerability?
One of the main benefits to our customers who choose to use the Azure Linux distro is the commitment to keep it up to date with the most recent and most secure versions of the open source libraries with which the distro is composed. Microsoft is committed to transparency in this work which is why we began publishing CSAF/VEX in October 2025. See this blog post for more information. If impact to additional products is identified, we will update the CVE to reflect this.
Mariner: Mariner
apache: apache
Customer Action Required: Yes
Remediation: CBL-Mariner Releases
Reference: https://learn.microsoft.com/en
Red Hat
httpd: mod_session: NULL pointer dereference when parsing Cookie header
vendor_redhat·2021-06-04·CVSS 7.5
CVE-2021-26690 [HIGH] CWE-476 httpd: mod_session: NULL pointer dereference when parsing Cookie header
httpd: mod_session: NULL pointer dereference when parsing Cookie header
Apache HTTP Server versions 2.4.0 to 2.4.46 A specially crafted Cookie header handled by mod_session can cause a NULL pointer dereference and crash, leading to a possible Denial Of Service
A NULL pointer dereference was found in Apache httpd mod_session. The highest threat from this vulnerability is to system availability.
Statement: This is a null pointer deference caused when using mod_session. It can result in crash of httpd child process by a remote attacker.
Mitigation: Only configurations which use the "SessionEnv" directive (which is not widely used) are vulnerable to this flaw. SessionEnv is not enabled in default configuration of httpd package shipped with Red Hat Products.
Package: httpd (Red Hat Enterpr
Debian
CVE-2021-26690: apache2 - Apache HTTP Server versions 2.4.0 to 2.4.46 A specially crafted Cookie header ha...
vendor_debian·2021·CVSS 7.5
CVE-2021-26690 [HIGH] CVE-2021-26690: apache2 - Apache HTTP Server versions 2.4.0 to 2.4.46 A specially crafted Cookie header ha...
Apache HTTP Server versions 2.4.0 to 2.4.46 A specially crafted Cookie header handled by mod_session can cause a NULL pointer dereference and crash, leading to a possible Denial Of Service
Scope: local
bookworm: resolved (fixed in 2.4.46-6)
bullseye: resolved (fixed in 2.4.46-6)
forky: resolved (fixed in 2.4.46-6)
sid: resolved (fixed in 2.4.46-6)
trixie: resolved (fixed in 2.4.46-6)
GHSA
GHSA-f669-j28w-pjvg: Apache HTTP Server versions 2
ghsa_unreviewed·2022-05-24
CVE-2021-26690 [HIGH] CWE-476 GHSA-f669-j28w-pjvg: Apache HTTP Server versions 2
Apache HTTP Server versions 2.4.0 to 2.4.46 A specially crafted Cookie header handled by mod_session can cause a NULL pointer dereference and crash, leading to a possible Denial Of Service
OSV
apache2 vulnerabilities
osv·2021-06-21·CVSS 7.3
CVE-2020-35452 [HIGH] apache2 vulnerabilities
apache2 vulnerabilities
USN-4994-1 fixed several vulnerabilities in Apache. This update provides
the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.
Original advisory details:
Antonio Morales discovered that the Apache mod_auth_digest module
incorrectly handled certain Digest nonces. A remote attacker could possibly
use this issue to cause Apache to crash, resulting in a denial of service.
(CVE-2020-35452)
Antonio Morales discovered that the Apache mod_session module incorrectly
handled certain Cookie headers. A remote attacker could possibly use this
issue to cause Apache to crash, resulting in a denial of service.
(CVE-2021-26690)
Christophe Jaillet discovered that the Apache mod_session module
incorrectly handled certain SessionHeader values. A remote attacker could
OSV
apache2 vulnerabilities
osv·2021-06-21·CVSS 7.5
CVE-2020-13950 [HIGH] apache2 vulnerabilities
apache2 vulnerabilities
Marc Stern discovered that the Apache mod_proxy_http module incorrectly
handled certain requests. A remote attacker could possibly use this issue
to cause Apache to crash, resulting in a denial of service. This issue only
affected Ubuntu 20.04 LTS, Ubuntu 20.10, and Ubuntu 21.04. (CVE-2020-13950)
Antonio Morales discovered that the Apache mod_auth_digest module
incorrectly handled certain Digest nonces. A remote attacker could possibly
use this issue to cause Apache to crash, resulting in a denial of service.
(CVE-2020-35452)
Antonio Morales discovered that the Apache mod_session module incorrectly
handled certain Cookie headers. A remote attacker could possibly use this
issue to cause Apache to crash, resulting in a denial of service.
(CVE-2021-26690)
Christoph
OSV
CVE-2021-26690: Apache HTTP Server versions 2
osv·2021-06-10·CVSS 7.5
CVE-2021-26690 [HIGH] CVE-2021-26690: Apache HTTP Server versions 2
Apache HTTP Server versions 2.4.0 to 2.4.46 A specially crafted Cookie header handled by mod_session can cause a NULL pointer dereference and crash, leading to a possible Denial Of Service
No detection rules found.
No public exploits indexed.
http://httpd.apache.org/security/vulnerabilities_24.htmlhttp://www.openwall.com/lists/oss-security/2021/06/10/6https://lists.apache.org/thread.html/r7f2b70b621651548f4b6f027552f1dd91705d7111bb5d15cda0a68dd%40%3Cdev.httpd.apache.org%3Ehttps://lists.apache.org/thread.html/rae406c1d19c0dfd3103c96923dadac2af1cd0bad6905ab1ede153865%40%3Cannounce.httpd.apache.org%3Ehttps://lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3Ehttps://lists.debian.org/debian-lts-announce/2021/07/msg00006.htmlhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/https://security.gentoo.org/glsa/202107-38https://security.netapp.com/advisory/ntap-20210702-0001/https://www.debian.org/security/2021/dsa-4937https://www.oracle.com/security-alerts/cpuoct2021.htmlhttp://httpd.apache.org/security/vulnerabilities_24.htmlhttp://www.openwall.com/lists/oss-security/2021/06/10/6https://lists.apache.org/thread.html/r7f2b70b621651548f4b6f027552f1dd91705d7111bb5d15cda0a68dd%40%3Cdev.httpd.apache.org%3Ehttps://lists.apache.org/thread.html/rae406c1d19c0dfd3103c96923dadac2af1cd0bad6905ab1ede153865%40%3Cannounce.httpd.apache.org%3Ehttps://lists.apache.org/thread.html/re026d3da9d7824bd93b9f871c0fdda978d960c7e62d8c43cba8d0bf3%40%3Ccvs.httpd.apache.org%3Ehttps://lists.debian.org/debian-lts-announce/2021/07/msg00006.htmlhttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/https://security.gentoo.org/glsa/202107-38https://security.netapp.com/advisory/ntap-20210702-0001/https://www.debian.org/security/2021/dsa-4937https://www.oracle.com/security-alerts/cpuoct2021.html
2021-06-10
Published