CVE-2021-21321
highpriority · track · 41EPSS 0.018 · 79 %ileEUUSEPSS · scored 2026-10-28
fastify-reply-from is an npm package which is a fastify plugin to forward the current http request to another server. In fastify-reply-from before version 4.0.2, 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. In affected versions, it is possible. This is fixed in version 4.0.2.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 7.5–10
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (3)
Products and version ranges known to be affected.
- fastify-reply-from project fastify-reply-from< 4.0.2nvdUScpe:2.3:a:fastify-reply-from_project:fastify-reply-from:*:*:*:*:*:*:*:*
advisories (1)
Vendor and ecosystem advisories describing this.
- GHSA-qmw8-3v4g-gwj4Prefix escape2021-03-03ghsa · osvUS
### 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](https://www.first.org/cvss/calculator/3.1#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 git@cfware.com, 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: * Open an issue in [fastify-reply-from](https://github.com/fastify/fastify-reply-from) * Email us at [hello@matteocollina.com](mailto:hello@matteocollina.com)
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (14)
External citations — patches, advisories, analysis.
- https://github.com/fastify/fastify-reply-from/commit/dea227dda606900cc01870d08541b4dcc69d3889cnnvd
- https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-qmw8-3v4g-gwj4cnnvd
- https://nvd.nist.gov/vuln/detail/CVE-2021-21321cnnvd
- https://packetstormsecurity.com/files/162151/Red-Hat-Security-Advisory-2021-1168-01.htmlcnnvd
- https://vigilance.fr/vulnerability/Node-js-Modules-five-vulnerabilities-34738cnnvd
- https://www.auscert.org.au/bulletins/ESB-2021.1225cnnvd
- https://www.auscert.org.au/bulletins/ESB-2021.2657cnnvd
- https://www.npmjs.com/package/fastify-reply-fromcnnvd
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