CVE-2021-29492
Published May 28, 2021
Last updated 3 years ago
Overview
- 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 based access control is configured, one may reconfigure the back end server to not treat `%2F` and `/` and `%5C` and `\` interchangeably.
- Source
- security-advisories@github.com
- NVD status
- Analyzed
Risk scores
CVSS 3.1
- Type
- Primary
- Base score
- 8.3
- Impact score
- 3.7
- Exploitability score
- 3.9
- Vector string
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
- Severity
- HIGH
CVSS 2.0
- Type
- Primary
- Base score
- 7.5
- Impact score
- 6.4
- Exploitability score
- 10
- Vector string
- AV:N/AC:L/Au:N/C:P/I:P/A:P
Weaknesses
- security-advisories@github.com
- CWE-22
Social media
- Hype score
- Not currently trending
Configurations
[
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "EE9E311E-85FF-42AA-B0A3-C138D436932D",
"versionEndExcluding": "1.15.5"
},
{
"criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "D36D66BB-9C95-4E59-AA78-6824ACCB89D7",
"versionEndExcluding": "1.16.4",
"versionStartIncluding": "1.16.0"
},
{
"criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "D502D5F9-38A7-46B1-890D-2A177B76AEBB",
"versionEndExcluding": "1.17.3",
"versionStartIncluding": "1.17.0"
},
{
"criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "BA3D8EC7-7D60-41C5-9770-3521DB6F7650",
"versionEndExcluding": "1.18.3",
"versionStartIncluding": "1.18.0"
}
],
"operator": "OR"
}
]
}
]