Use After Free in Envoyproxy Envoy
CVE-2021-43825
Envoy is an open source edge and service proxy, designed for cloud-native applications. Sending a locally generated response must stop further processing of request or response data. Envoy tracks the amount of buffered request and response data and aborts the request if the amount of buffered data is over the limit by sending 413 or 500 responses. However when the buffer overflows while response is processed by the filter chain the operation may not be aborted correctly and result in accessing a freed memory block. If this happens Envoy will crash resulting in a denial of service.
Vulnerability class: Use-After-Free
EPSS: 0.009 (55.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:L.
Affected products
- Envoyproxy Envoy — versions < 1.18.6, >= 1.19.0, < 1.19.3, >= 1.20.0, < 1.20.2
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory, Issue Tracking)
- security-advisories@github.com (Patch, Third Party Advisory, x_refsource_MISC)
Frequently asked questions
- What is CVE-2021-43825?
- CVE-2021-43825 is a medium-severity vulnerability in Envoyproxy Envoy, classified under Use After Free. CVSS score: 6.1/10. Published 2022-02-22.
- How severe is CVE-2021-43825?
- Medium severity. CVSS v3 base score is 6.1 out of 10.
- Is CVE-2021-43825 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.