fastify-bearer-auth: Observable Discrepancy
CVE-2022-31142 is a high-severity observable discrepancy vulnerability in fastify-bearer-auth from Fastify, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected fastify-bearer-auth versions: >= 5.0.1, < 7.0.2; = 8.0.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.53% chance of exploitation within 30 days, higher than 75% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Bearer-auth to 7.0.2 or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Fastify | fastify-bearer-auth | >= 5.0.1, < 7.0.2; = 8.0.0 | Not stated |
| Fastify | Bearer-auth | 5.0.1 up to, but not including, 7.0.2; 8.0.0 | 7.0.2 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | CNA (github.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
@fastify/bearer-auth is a Fastify plugin to require bearer Authorization headers. @fastify/bearer-auth prior to versions 7.0.2 and 8.0.1 does not securely use crypto.timingSafeEqual. A malicious attacker could estimate the length of one valid bearer token. According to the corresponding RFC 6750, the bearer token has only base64 valid characters, reducing the range of characters for a brute force attack. Version 7.0.2 and 8.0.1 of @fastify/bearer-auth contain a patch. There are currently no known workarounds. The package fastify-bearer-auth, which covers versions 6.0.3 and prior, is also vulnerable starting at version 5.0.1. Users of fastify-bearer-auth should upgrade to a patched version of @fastify/bearer-auth.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Observable Discrepancy
The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.
How developers prevent this class of flaw
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- github.com/fastify/fastify-bearer-auth/security/advisories/GHSA-376v-xgjx-7mfrThird Party Advisory
Patches and release notes
- github.com/fastify/fastify-bearer-auth/commit/0c468a616d7e56126dc468150f6a5a92e530b8e4Third Party Advisory
- github.com/fastify/fastify-bearer-auth/commit/39353b15409ee99474545f615ffb16180cf3b716Third Party Advisory
- github.com/fastify/fastify-bearer-auth/commit/f921a0582dc83112039004a9b5041141b50c5b3fThird Party Advisory
Third-party and government advisories
- hackerone.com/reports/1633287Permissions Required, Third Party Advisory
Recent Observable Discrepancy vulnerabilities
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
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