CVE-2026-112712: @fastify/middie vulnerable to path-scoped middleware bypass via scope prefix mismatch
Noroxi assessment
Priority: Monitor (action score 36/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.31% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: @fastify/middie @fastify/middie 9.3.6.
Low priority for now. Upgrade to @fastify/middie @fastify/middie 9.3.6 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
@fastify/middie is the Express-style middleware engine for Fastify. In versions from 9.0.0 through 9.3.5, the use() function joined a path-scoped middleware's mount path to the plugin scope prefix in a way that could diverge from the path Fastify's router serves, most often when the scope prefix ended in a slash, and also for array mount paths and for mount paths written without a leading slash. When the two paths disagreed, the middleware was silently skipped while the route handler still ran, so path-scoped middleware such as authentication, authorization, or rate limiting could be bypassed by a single unauthenticated request. The issue is fixed in @fastify/middie 9.3.6, and users should upgrade to 9.3.6 or later. As a workaround, enforce authorization in a Fastify hook such as preHandler that runs after the router has resolved the request.
- Published
- Oct 20, 2026
- Updated
- Oct 22, 2026
- EPSS
- 0.3% · 24th percentile
- CWE
- CWE-436
Report tools
Action score
36
Monitor
Low priority for now.
- CVSS
- 36 / 40 · 9.1 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.3%
CNA vs NVD score
- NVD
- —
- CNA · openjs
- 9.1
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (openjs). Independent of NVD's CPE analysis and usually ahead of it.
@fastify/middie @fastify/middie
- 9.3.6not affected
- 9.0.0 and later · before 9.3.6affected · semver
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| @fastify/middie @fastify/middie | 9.3.6 | Vendor (CNA) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Published
- Fix recordedsame day
- TodayOct 27, 2026+7 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- zachariah-mithanireporter
- mcollinaremediation developer
- UlisesGasconremediation developer
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- None
Weakness class (CWE)
CWE-436 · Interpretation ConflictCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Change log
- Exploit maturity— → none
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (1 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.