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Prefix escape

Critical severity GitHub Reviewed Published Feb 23, 2021 in fastify/fastify-reply-from • Updated Feb 1, 2023

Package

npm fastify-reply-from (npm)

Affected versions

< 4.0.2

Patched versions

4.0.2

Description

Impact

By crafting a specific URL, it is possible to escape the prefix of the proxied backend service.
If the base url of the proxied server is /pub/, a user expect that accessing /priv on the target service would not be possible. Unfortunately, it is.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

Patches

A patch have been submitted by Corey Farrell [email protected], the reporter.
All releases after v4.0.2 include the fix.

Workarounds

There are no workaround available.

For more information

If you have any questions or comments about this advisory:

References

@mcollina mcollina published to fastify/fastify-reply-from Feb 23, 2021
Reviewed Mar 2, 2021
Published by the National Vulnerability Database Mar 2, 2021
Published to the GitHub Advisory Database Mar 3, 2021
Last updated Feb 1, 2023

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N

EPSS score

0.307%
(70th percentile)

Weaknesses

CVE ID

CVE-2021-21321

GHSA ID

GHSA-qmw8-3v4g-gwj4

Source code

No known source code
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