VulnerabilityAnalyzed

CVE-2026-16158

Impact: @fastify/reply-from versions from 8.3.1 up to but not including 12.6.4 build the internal URL cache key by concatenating the destination and source path without a delimiter.

CRITICAL 10.0EPSS 0.23%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.23%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

Impact: @fastify/reply-from versions from 8.3.1 up to but not including 12.6.4 build the internal URL cache key by concatenating the destination and source path without a delimiter. Different destination and source pairs can therefore produce the same key while resolving to different upstream URLs. When getUpstream selects an upstream from request data, a URL cached for one upstream can be reused for a request intended for another upstream, causing cross-upstream data access and modification. The default configuration is affected. Setting disableCache to true prevents the behavior. Patches: upgrade to @fastify/reply-from 12.6.4. Workarounds: pass disableCache: true when registering the plugin.

CVSS 3.1: 10.0 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
EPSS: 0.23% probability · 14th percentile
CISA KEV: Not listed
Weakness: CWE-441
Affected: fastify/fastify\/reply-from
Source: ce714d77-add3-4f53-aff5-83d477b104bb

References

https://cna.openjsf.org/security-advisories.htmlVendor Advisory
https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-v574-6498-x57vVendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.