CVE-2021-33193
Request splitting via HTTP/2 method injection and mod_proxy
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
1Exploited in Wild
-Decision
Descriptions
A crafted method sent through HTTP/2 will bypass validation and be forwarded by mod_proxy, which can lead to request splitting or cache poisoning. This issue affects Apache HTTP Server 2.4.17 to 2.4.48.
Un método diseñado enviado mediante HTTP/2 omitirá la comprobación y será reenviado por mod_proxy, lo que puede conllevar a la división de peticiones o el envenenamiento de la caché. Este problema afecta a Apache HTTP Server versiones 2.4.17 a 2.4.48.
A NULL pointer dereference was found in Apache httpd mod_h2. The highest threat from this flaw is to system integrity.
USN-5090-1 fixed vulnerabilities in Apache HTTP Server. One of the upstream fixes introduced a regression in UDS URIs. This update fixes the problem. James Kettle discovered that the Apache HTTP Server HTTP/2 module incorrectly handled certain crafted methods. A remote attacker could possibly use this issue to perform request splitting or cache poisoning attacks. It was discovered that the Apache HTTP Server incorrectly handled certain malformed requests. A remote attacker could possibly use this issue to cause the server to crash, resulting in a denial of service. Li Zhi Xin discovered that the Apache mod_proxy_uwsgi module incorrectly handled certain request uri-paths. A remote attacker could possibly use this issue to cause the server to crash, resulting in a denial of service. This issue only affected Ubuntu 20.04 LTS and Ubuntu 21.04. It was discovered that the Apache HTTP Server incorrectly handled escaping quotes. If the server was configured with third-party modules, a remote attacker could use this issue to cause the server to crash, resulting in a denial of service, or possibly execute arbitrary code. It was discovered that the Apache mod_proxy module incorrectly handled certain request uri-paths. A remote attacker could possibly use this issue to cause the server to forward requests to arbitrary origin servers. Various other issues were also addressed.
CVSS Scores
SSVC
- Decision:-
Timeline
- 2021-05-19 CVE Reserved
- 2021-08-16 CVE Published
- 2024-08-03 CVE Updated
- 2024-08-03 First Exploit
- 2025-03-30 EPSS Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
CWE
- CWE-476: NULL Pointer Dereference
CAPEC
References (15)
URL | Date | SRC |
---|---|---|
https://portswigger.net/research/http2 | 2024-08-03 |
Affected Vendors, Products, and Versions
Vendor | Product | Version | Other | Status | ||||||
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Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
Apache Search vendor "Apache" | Http Server Search vendor "Apache" for product "Http Server" | >= 2.4.17 <= 2.4.48 Search vendor "Apache" for product "Http Server" and version " >= 2.4.17 <= 2.4.48" | - |
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
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Tenable Search vendor "Tenable" | Tenable.sc Search vendor "Tenable" for product "Tenable.sc" | <= 5.19.1 Search vendor "Tenable" for product "Tenable.sc" and version " <= 5.19.1" | - |
Affected
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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
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