CVE-2021-33193
HIGHCVSS 7.5/10EPSS 46.18%
Last modified
CVE-2021-33193 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.. EPSS estimates a 46.18% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Debian | Debian Linux | 10.0 |
| Apache | Http Server | >= 2.4.17, < 2.4.49 |
| Fedoraproject | Fedora | 34 |
| Fedoraproject | Fedora | 35 |
| Tenable | Tenable.Sc | <= 5.19.1 |
| Oracle | Secure Backup | < 18.1.0.1.0 |
| Oracle | Zfs Storage Appliance Kit | 8.8 |
References
- https://lists.debian.org/debian-lts-announce/2023/03/msg00002.htmlMailing List, Third Party Advisory
- https://portswigger.net/research/http2Exploit, Third Party Advisory
- https://security.gentoo.org/glsa/202208-20Third Party Advisory
- https://security.netapp.com/advisory/ntap-20210917-0004/Third Party Advisory
- https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
- https://www.tenable.com/security/tns-2021-17Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2023/03/msg00002.htmlMailing List, Third Party Advisory
- https://portswigger.net/research/http2Exploit, Third Party Advisory
- https://security.gentoo.org/glsa/202208-20Third Party Advisory
- https://security.netapp.com/advisory/ntap-20210917-0004/Third Party Advisory
- https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
- https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
- https://www.tenable.com/security/tns-2021-17Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2021-33193?
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.
How severe is CVE-2021-33193?
CVE-2021-33193 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 46.18% probability of exploitation in the next 30 days.
How do I fix CVE-2021-33193?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-33193?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST