CVE-2025-46821
Envoyproxy Envoy ≤ 1.31.8
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NSummary
CVE-2025-46821 is a medium-severity Overly Restrictive Regular Expression (CWE-186) vulnerability in Envoyproxy Envoy. Its CVSS base score is 5.3 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 18th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-13934
Vulnerability Data
Envoy is a cloud-native edge/middle/service proxy. Prior to versions 1.34.1, 1.33.3, 1.32.6, and 1.31.8, Envoy's URI template matcher incorrectly excludes the `*` character from a set of valid characters in the URI path. As a result URI path containing the…
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`*` character will not match a URI template expressions. This can result in bypass of RBAC rules when configured using the `uri_template` permissions. This vulnerability is fixed in Envoy versions v1.34.1, v1.33.3, v1.32.6, v1.31.8. As a workaround, configure additional RBAC permissions using `url_path` with `safe_regex` expression.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Requiring explicit validation of inputs structurally forces regex patterns to be written so they actually catch dangerous values rather than missing them due to over-restriction.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly require correct, non-overly-restrictive regex patterns for validation and detection logic.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development can detect overly restrictive regex through negative-test cases.
Secure development lifecycle includes input-validation and regex-review practices that can catch overly restrictive patterns.
Application security requirements explicitly call for correct validation rules, reducing the risk of overly restrictive regex.
Secure coding standards directly mandate proper regex design and testing, largely preventing this weakness.