CVE-2023-51701
@fastify-reply-from JSON Content-Type parsing confusion
fastify-reply-from is a Fastify plugin to forward the current HTTP request to another server. A reverse proxy server built with @fastify/reply-from could misinterpret the incoming body by passing an header ContentType: application/json ; charset=utf-8. This can lead to bypass of security checks. This vulnerability has been patched in '@fastify/reply-from` version 9.6.0.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
@fastify-reply-from JSON Content-Type parsing confusion
fastify-reply-from is a Fastify plugin to forward the current HTTP request to another server. A reverse proxy server built with @fastify/reply-from could misinterpret the incoming body by passing an header ContentType: application/json ; charset=utf-8. This can lead to bypass of security checks. This vulnerability has been patched in '@fastify/reply-from` version 9.6.0.
- Record
CVE-2023-51701- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-444
- Updated
- 2026-11-02
EUVDEUVD-2024-0427
fastify-reply-from is a Fastify plugin to forward the current HTTP request to another server. A reverse proxy server built with @fastify/reply-from could misinterpret the incoming body by passing an header ContentType: application/json ; charset=utf-8. This can lead to bypass of security checks. This vulnerability has been patched in '@fastify/reply-from` version 9.6.0.
- Record
EUVD-2024-0427- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-v2v2-hph8-q5xp
@fastify/reply-from JSON Content-Type parsing confusion
Impact
The main repo of fastify use fast-content-type-parse to parse request Content-Type, which will trim after split.
The fastify-reply-from have not use this repo to unify the parse of Content-Type, which won't trim.
As a result, a reverse proxy server built with @fastify/reply-from could misinterpret the incoming body by passing an header ContentType: application/json ; charset=utf-8. This can lead to bypass of security checks.
Patches
@fastify/reply-from v9.6.0 include the fix.
Workarounds
There are no known workarounds.
References
Hackerone Report: https://hackerone.com/reports/2295770.
- Record
GHSA-v2v2-hph8-q5xp- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-444
- Updated
- 2026-11-02
NVD
fastify-reply-from is a Fastify plugin to forward the current HTTP request to another server. A reverse proxy server built with @fastify/reply-from could misinterpret the incoming body by passing an header ContentType: application/json ; charset=utf-8. This can lead to bypass of security checks. This vulnerability has been patched in '@fastify/reply-from` version 9.6.0.
- Record
CVE-2023-51701- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Weakness
- CWE-444
- Updated
- 2026-11-02
OSV
@fastify-reply-from JSON Content-Type parsing confusion
fastify-reply-from is a Fastify plugin to forward the current HTTP request to another server. A reverse proxy server built with @fastify/reply-from could misinterpret the incoming body by passing an header ContentType: application/json ; charset=utf-8. This can lead to bypass of security checks. This vulnerability has been patched in '@fastify/reply-from` version 9.6.0.
- Record
CVE-2023-51701- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-444
- Updated
- 2026-11-02
OSVGHSA-v2v2-hph8-q5xp
@fastify/reply-from JSON Content-Type parsing confusion
Impact
The main repo of fastify use fast-content-type-parse to parse request Content-Type, which will trim after split.
The fastify-reply-from have not use this repo to unify the parse of Content-Type, which won't trim.
As a result, a reverse proxy server built with @fastify/reply-from could misinterpret the incoming body by passing an header ContentType: application/json ; charset=utf-8. This can lead to bypass of security checks.
Patches
@fastify/reply-from v9.6.0 include the fix.
Workarounds
There are no known workarounds.
References
Hackerone Report: https://hackerone.com/reports/2295770.
- Record
GHSA-v2v2-hph8-q5xp- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-444
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
@fastify/reply-fromnpm |
before 9.6.0 | 9.6.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-51701 is a medium vulnerability (CVSS 5.3) in Fastify Fastify-reply-from, published January 8, 2024. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.48%, the 41st percentile. Fixed in @fastify/reply-from 9.6.0.
References
github.com/fastify/fastify-reply-from/security/advisories/GHSA-v2v2-hph8-q5xp
nvd.nist.gov/vuln/detail/CVE-2023-51701