CVE-2021-33193

Exploitation

Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.

SSVC decision

Not assessed by CISA

EPSS probability

46.18% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 98.7% of scored records. A rank, not a probability.

NVD base score

7.5 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

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

NVD analysis status

Analyzed. NVD last modified this record on 2026-06-17.

Red Hat severity

Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2021-08-16 00:00Z5 YR AGO

Last updated

2024-08-03 23:42Z2 YR AGO

Reserved

2021-05-19

Assigning CNA

apache

Record state

PUBLISHED

Severity

Not rated by the issuing CNA

CNA CVSS vector

Not published by the issuing CNA

Weaknesses

• CWE-476NULL Pointer DereferenceBase

Data version

5.1

Document digest

e23c35ab747aa21ee46e4ee446960cb85d5ed8423d4b6111807cf1ea229d9ba5

• portswigger.nethttps://portswigger.net/research/http2
• github.comhttps://github.com/apache/httpd/commit/ecebcc035ccd8d0e2984fe41420d9e944f456b3c.patch
• lists.apache.org[httpd-cvs] 20210916 [httpd-site] branch main updated: Revert "Add descriptions for CVE-2021-33193 CVE-2021-36160"https://lists.apache.org/thread.html/re4162adc051c1a0a79e7a24093f3776373e8733abaff57253fef341d%40%3Ccvs.httpd.apache.org%3Emailing-list
• lists.apache.org[httpd-cvs] 20210916 [httpd-site] branch main updated: Add descriptions for CVE-2021-33193 CVE-2021-36160https://lists.apache.org/thread.html/ree7519d71415ecdd170ff1889cab552d71758d2ba2904a17ded21a70%40%3Ccvs.httpd.apache.org%3Emailing-list
• lists.fedoraproject.orgFEDORA-2021-5d2d4b6ac5https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DSM6UWQICBJ2TU727RENU3HBKEAFLT6T/vendor-advisory
• lists.fedoraproject.orgFEDORA-2021-f94985afcahttps://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EUVJVRJRBW5QVX4OY3NOHZDQ3B3YOTSG/vendor-advisory
• tools.cisco.com20211124 Multiple Vulnerabilities in Apache HTTP Server Affecting Cisco Products: November 2021https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-2.4.49-VWL69sWQvendor-advisory
• www.oracle.comhttps://www.oracle.com/security-alerts/cpujan2022.html
• security.netapp.comhttps://security.netapp.com/advisory/ntap-20210917-0004/
• www.tenable.comhttps://www.tenable.com/security/tns-2021-17
• www.oracle.comhttps://www.oracle.com/security-alerts/cpuapr2022.html
• security.gentoo.orgGLSA-202208-20https://security.gentoo.org/glsa/202208-20vendor-advisory
• lists.debian.org[debian-lts-announce] 20230303 [SECURITY] [DLA 3351-1] apache2 security updatehttps://lists.debian.org/debian-lts-announce/2023/03/msg00002.htmlmailing-list