CVE-2021-28683
HIGHCVSS 7.5/10EPSS 1.69%
Last modified
CVE-2021-28683 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. An issue was discovered in Envoy through 1.71.1. There is a remotely exploitable NULL pointer dereference and crash in TLS when an unknown TLS alert code is received.. EPSS estimates a 1.69% chance of exploitation in the next 30 days.
Description
An issue was discovered in Envoy through 1.71.1. There is a remotely exploitable NULL pointer dereference and crash in TLS when an unknown TLS alert code is received.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Envoyproxy | Envoy | 1.16.2 |
| Envoyproxy | Envoy | 1.17.1 |
References
- https://blog.envoyproxy.ioVendor Advisory
- https://github.com/envoyproxy/envoy/releasesThird Party Advisory
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-r22g-5f3x-xjggNot Applicable, Third Party Advisory
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-xw4q-6pj2-5gfgThird Party Advisory
- https://blog.envoyproxy.ioVendor Advisory
- https://github.com/envoyproxy/envoy/releasesThird Party Advisory
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-r22g-5f3x-xjggNot Applicable, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2021-28683?
An issue was discovered in Envoy through 1.71.1. There is a remotely exploitable NULL pointer dereference and crash in TLS when an unknown TLS alert code is received.
How severe is CVE-2021-28683?
CVE-2021-28683 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.69% probability of exploitation in the next 30 days.
How do I fix CVE-2021-28683?
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-2021-28683?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST