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CVE-2021-34798

61
FAUCET Score

CVE-2021-34798 is a high-severity vulnerability affecting Apache HTTP Server versions 2.4.48 and earlier, as well as products from vendors like Broadcom, Debian, and Oracle. Malformed requests can lead to a NULL pointer dereference, potentially causing a denial of service. With a CVSS score of 7.5, this vulnerability is easily exploitable over the network without user interaction. While there is no known active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered some community discussion and media coverage, indicating awareness.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.4.48CPE matchmatch criteria
cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
35CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
64.51%
Probability of exploitation in next 30 days
EPSS Percentile
99.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.6451 is in the 99th percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (36)

apachepatch availablevia llm_extracted
Fixed in: 2.4
microsoftpatch availablevia msrc
Product: 16886-16820Fixed in: 2.4.49-1
microsoftpatch availablevia msrc
Product: cbl2 httpd 2.4.52-1 on CBL Mariner 2.0Fixed in: 2.4.52-1
microsoftpatch availablevia msrc
Product: cm1 httpd 2.4.49-1 on CBL Mariner 1.0Fixed in: 2.4.49-1
microsoftpatch availablevia msrc
Product: 17030-16823Fixed in: 2.4.52-1
oraclepatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-mod_cluster-native-0:1.3.16-9.Final_redhat_2.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-mod_http2-0:1.15.7-21.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-mod_jk-0:1.2.48-20.redhat_1.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-mod_md-1:2.0.8-40.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-mod_security-0:2.9.2-67.GA.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-nghttp2-0:1.39.2-39.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-openssl-1:1.1.1g-8.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-openssl-chil-0:1.0.0-7.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-openssl-pkcs11-0:0.4.10-22.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-apr-0:1.6.3-107.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-apr-util-0:1.6.1-84.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-curl-0:7.78.0-2.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-httpd-0:2.4.37-78.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_cluster-native-0:1.3.16-9.Final_redhat_2.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_http2-0:1.15.7-21.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_jk-0:1.2.48-20.redhat_1.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_md-1:2.0.8-40.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-mod_security-0:2.9.2-67.GA.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-nghttp2-0:1.39.2-39.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-openssl-1:1.1.1g-8.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-openssl-chil-0:1.0.0-7.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services on RHEL 7Fixed in: jbcs-httpd24-openssl-pkcs11-0:0.4.10-22.jbcs.el7
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: httpd-0:2.4.6-97.el7_9.4
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: httpd:2.4-8050020220228164203.c5368500
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Software Collections for Red Hat Enterprise Linux 7Fixed in: httpd24-httpd-0:2.4.34-23.el7.5
View patch
redhatpatch availablevia redhat_api
Product: Text-Only JBCS
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-httpd-0:2.4.37-78.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-curl-0:7.78.0-2.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-apr-util-0:1.6.1-84.el8jbcs
View patch
redhatpatch availablevia redhat_api
Product: JBoss Core Services for RHEL 8Fixed in: jbcs-httpd24-apr-0:1.6.3-107.el8jbcs
View patch

Vendor Advisories (5)

apachellm-apache-f398f8ed28802aa3LOW

Apache HTTP Server 2.4 vulnerabilities - The Apache HTTP Server Project

Mar 2, 2026
apachellm-apache-a7a91ec4c0e9421dHIGH

Apache HTTP Server 2.4 vulnerabilities - The Apache HTTP Server Project

Dec 10, 2025
redhatCVE-2021-34798Moderate

httpd: NULL pointer dereference via malformed requests

Sep 16, 2021
microsoft2021-Sep/CVE-2021-34798Important

NULL pointer dereference in httpd core

Sep 14, 2021
apachellm-apache-684e4d0003611bd4LOW

Apache HTTP Server 2.4 vulnerabilities - The Apache HTTP Server Project

References

httpd.apache.org / security/vulnerabilities_24.html
Release NotesVendor Advisory
cert-portal.siemens.com / productcert/pdf/ssa-685781.pdf
PatchThird Party Advisory
kc.mcafee.com / corporate/index
Third Party Advisory
lists.apache.org / thread.html/r3925e167d5eb1c75def3750c155d753064e1d34a143028bb32910432%40%3Cusers.httpd.apache.org%3E
lists.apache.org / thread.html/r61fdbfc26ab170f4e6492ef3bd5197c20b862ce156e9d5a54d4b899c%40%3Cusers.httpd.apache.org%3E
lists.apache.org / thread.html/r82838efc5fa6fc4c73986399c9b71573589f78b31846aff5bd9b1697%40%3Cusers.httpd.apache.org%3E
lists.apache.org / thread.html/r82c077663f9759c7df5a6656f925b3ee4f55fcd33c889ba7cd687029%40%3Cusers.httpd.apache.org%3E
lists.debian.org / debian-lts-announce/2021/10/msg00001.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R
security.gentoo.org / glsa/202208-20
Third Party Advisory
security.netapp.com / advisory/ntap-20211008-0004
Third Party Advisory
tools.cisco.com / security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-2.4.49-VWL69sWQ
Third Party Advisory
debian.org / security/2021/dsa-4982
Third Party Advisory
oracle.com / security-alerts/cpuapr2022.html
PatchThird Party Advisory
oracle.com / security-alerts/cpujan2022.html
PatchThird Party Advisory
tenable.com / security/tns-2021-17
Third Party Advisory