CVE-2021-29492
8.1 · HIGHOverview
CVE-2021-29492 is a high-severity vulnerability affecting envoyproxy envoy. It was published on May 28, 2021 and has a CVSS 3.1 base score of 8.1 (HIGH).
This vulnerability has a CVSS 3.1 base score of 8.1, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
Envoy is a cloud-native edge/middle/service proxy. Envoy does not decode escaped slash sequences `%2F` and `%5C` in HTTP URL paths in versions 1.18.2 and before. A remote attacker may craft a path with escaped slashes, e.g. `/something%2F..%2Fadmin`, to bypass access control, e.g. a block on `/admin`. A backend server could then decode slash sequences and normalize path and provide an attacker access beyond the scope provided for by the access control policy. ### Impact Escalation of Privileges when using RBAC or JWT filters with enforcement based on URL path. Users with back end servers that interpret `%2F` and `/` and `%5C` and `\` interchangeably are impacted. ### Attack Vector URL paths containing escaped slash characters delivered by untrusted client. Patches in versions 1.18.3, 1.17.3, 1.16.4, 1.15.5 contain new path normalization option to decode escaped slash characters. As a workaround, if back end servers treat `%2F` and `/` and `%5C` and `\` interchangeably and a URL path ba
Remediation
Check the references section for vendor advisories and patches from envoyproxy. Update envoy to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| envoyproxy | envoy | >= 0, < 1.15.5 | Affected |
Frequently Asked Questions
What is CVE-2021-29492?
CVE-2021-29492 is a high-severity vulnerability affecting envoyproxy envoy. It was published on May 28, 2021 and has a CVSS 3.1 base score of 8.1 (HIGH).
How severe is CVE-2021-29492?
This vulnerability has a CVSS 3.1 base score of 8.1, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-29492?
Check the references section for vendor advisories and patches from envoyproxy. Update envoy to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-29492?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-29492 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
AI-driven PR review catches vulnerable dependencies before they ship.
Browser-based exploitation validates findings with real proof-of-concept.
Related HIGH CVEs from 2021
View all →systeminformation is an open source system and OS information library for node.js. A command injecti
An Improper Access Control Privilege Escalation Vulnerability was discovered in the User Setting of
An SQL injection Privilege Escalation Vulnerability was discovered in the Orion Platform reported by
Insecure deserialization leading to Remote Code Execution was detected in the Orion Platform version
Insecure Deserialization of untrusted data remote code execution vulnerability was discovered in Pat
Deserialization of Untrusted Data in the Web Console Chart Endpoint can lead to remote code executio
Insecure Deseralization of untrusted data remote code execution vulnerability was discovered in Patc
SAP Web Dispatcher versions - 7.49, 7.53, 7.77, 7.81, KRNL64NUC - 7.22, 7.22EXT, 7.49, KRNL64UC -7.2
uploader.php in the KCFinder integration project through 2018-06-01 for Drupal mishandles validation
An issue was discovered in the PageLayer plugin before 1.1.2 for WordPress. The pagelayer_settings_p
MK-AUTH through 19.01 K4.9 allows CSRF for password changes via the central/executar_central.php?aca
IBM Cloud Pak System 2.3 is vulnerable to cross-site request forgery which could allow an attacker t