fast-uri vulnerable to host confusion via percent-encoded authority delimiters
fast-uri normalize() decoded percent-encoded authority delimiters inside the host component and then re-emitted them as raw delimiters during serialization. A host that combined an allowed domain, an encoded at-sign, and a different domain was re-emitted with the at-sign as a raw userinfo separator, changing the URI's authority to the second domain. Applications that normalize untrusted URLs before host allowlist checks, redirect validation, or outbound request routing can be steered to a different authority than the input appeared to specify. Versions <= 3.1.1 are affected. Update to 3.1.2 or later.
- Published
- May 5, 2026
- Updated
- Sep 10, 2026
- EPSS
- 0.7% · 50th percentile
- CWE
- CWE-436
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Report tools
Action score
30
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.7%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · openjs
- 7.5
- 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.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| openjsf | fast-uri | cpe:2.3:a:openjsf:fast-uri |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- openjsf fast-uribefore 3.1.2
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.
fast-uri fast-uri
- 3.1.2not affected
- before 3.1.2affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | node-ajv | all versions | — |
| Debian:14 | node-ajv | before 8.20.0~ds+~cs6.1.3-1 | 8.20.0~ds+~cs6.1.3-1 |
| npm | fast-uri | from 3.0.0 · before 3.1.2 | 3.1.2 |
| npm | fast-uri | before 2.4.1 | 2.4.1 |
| Red Hat:ansible_automation_platform_developer:2.6::el9 | automation-controller | before 0:4.7.13-2.el9ap | 0:4.7.13-2.el9ap |
| Red Hat:ansible_automation_platform_developer:2.6::el9 | automation-controller-cli | before 0:4.7.13-2.el9ap | 0:4.7.13-2.el9ap |
| Red Hat:ansible_automation_platform_developer:2.6::el9 | python3.12-urllib3 | before 0:2.7.0-1.el9ap | 0:2.7.0-1.el9ap |
| Red Hat:ansible_automation_platform:2.6::el9 | automation-controller-server | before 0:4.7.13-2.el9ap | 0:4.7.13-2.el9ap |
| Red Hat:ansible_automation_platform:2.6::el9 | automation-controller-ui | before 0:4.7.13-2.el9ap | 0:4.7.13-2.el9ap |
| Red Hat:ansible_automation_platform:2.6::el9 | automation-controller-venv-tower | before 0:4.7.13-2.el9ap | 0:4.7.13-2.el9ap |
| Red Hat:ansible_automation_platform:2.6::el9 | automation-platform-ui | before 0:2.6.10-1.el9ap | 0:2.6.10-1.el9ap |
| Red Hat:ansible_automation_platform:2.6::el9 | python3.12-pyjwt | before 0:2.13.0-1.el9ap | 0:2.13.0-1.el9ap |
| Red Hat:ansible_automation_platform:2.6::el9 | python3.12-pyjwt+crypto | before 0:2.13.0-1.el9ap | 0:2.13.0-1.el9ap |
| Red Hat:enterprise_linux:10.2 | rh-podman-desktop | before 0:1.1.1-1.el10_2 | 0:1.1.1-1.el10_2 |
| Red Hat:hummingbird:1 | grafana13.1 | before 0:13.1.3-0.3.hum1 | 0:13.1.3-0.3.hum1 |
Same product
openjsf: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-84394fast-uri vulnerable to host confusion via an unclosed bracket in the URI authority30Monitor
- CVE-2026-84292fast-uri vulnerable to authority injection via an unvalidated port in serialize30Monitor
- CVE-2026-76172fast-uri vulnerable to host confusion via percent-encoded scheme normalization30Monitor
- CVE-2026-75975fast-uri vulnerable to server-side request forgery via malformed IPv6 normalization30Monitor
- CVE-2026-75931fast-uri vulnerable to host confusion via skipped IDN canonicalization on scheme-relative references30Monitor
- CVE-2026-75899fast-uri vulnerable to server-side request forgery via repeated hostname percent-decoding30Monitor
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 |
|---|---|---|
| fast-uri fast-uri | 3.1.2 | Vendor (CNA) |
| debian:node-ajv | 8.20.0~ds+~cs6.1.3-1 · Debian:14 | Package registry (OSV) |
| npm:fast-uri | 2.4.1 | Package registry (OSV) |
| npm:fast-uri | 3.1.2 | Package registry (OSV) |
| red hat:automation-controller | 0:4.7.13-2.el9ap · Red Hat:ansible_automation_platform_developer:2.6::el9 | Package registry (OSV) |
| red hat:automation-controller-cli | 0:4.7.13-2.el9ap · Red Hat:ansible_automation_platform_developer:2.6::el9 | Package registry (OSV) |
| red hat:automation-controller-server | 0:4.7.13-2.el9ap · Red Hat:ansible_automation_platform:2.6::el9 | Package registry (OSV) |
| red hat:automation-controller-ui | 0:4.7.13-2.el9ap · Red Hat:ansible_automation_platform:2.6::el9 | Package registry (OSV) |
| red hat:automation-controller-venv-tower | 0:4.7.13-2.el9ap · Red Hat:ansible_automation_platform:2.6::el9 | Package registry (OSV) |
| red hat:automation-platform-ui | 0:2.6.10-1.el9ap · Red Hat:ansible_automation_platform:2.6::el9 | Package registry (OSV) |
| red hat:grafana13.1 | 0:13.1.3-0.3.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| red hat:python3.12-pyjwt | 0:2.13.0-1.el9ap · Red Hat:ansible_automation_platform:2.6::el9 | Package registry (OSV) |
| red hat:python3.12-pyjwt+crypto | 0:2.13.0-1.el9ap · Red Hat:ansible_automation_platform:2.6::el9 | Package registry (OSV) |
| red hat:python3.12-urllib3 | 0:2.7.0-1.el9ap · Red Hat:ansible_automation_platform_developer:2.6::el9 | Package registry (OSV) |
| red hat:rh-podman-desktop | 0:1.1.1-1.el10_2 · Red Hat:enterprise_linux:10.2 | Package registry (OSV) |
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.
No dated events beyond publication.
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.
- Jvrreporter
- Matteo Collinaremediation developer
- KaKaremediation reviewer
- Ulises Gascónremediation developer
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-1367655 days apartfast-uri vulnerable to host confusion via failed IDN canonicalization30Monitor
- CVE-2026-1622175 days apartfast-uri vulnerable to host confusion via literal backslash authority delimiter30Monitor
- CVE-2026-1844687 days apartfast-uri vulnerable to host confusion via backslash authority introducer30Monitor
- CVE-2026-75931111 days apartfast-uri vulnerable to host confusion via skipped IDN canonicalization on scheme-relative references30Monitor
- CVE-2026-84394121 days apartfast-uri vulnerable to host confusion via an unclosed bracket in the URI authority30Monitor
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
- none
- 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
- None
- 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:N/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
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- cna.openjsf.org/security-advisories.html
- github.com/fastify/fast-uri/security/advisories/GHSA-v39h-62p7-jpjc
- access.redhat.com/errata/RHSA-2026:25271
- access.redhat.com/errata/RHSA-2026:25273
- access.redhat.com/errata/RHSA-2026:26225
- access.redhat.com/errata/RHSA-2026:26234
- access.redhat.com/errata/RHSA-2026:28571
- access.redhat.com/errata/RHSA-2026:29197
- access.redhat.com/errata/RHSA-2026:29795
- access.redhat.com/errata/RHSA-2026:29796
- access.redhat.com/errata/RHSA-2026:29800
- access.redhat.com/errata/RHSA-2026:29834
- access.redhat.com/errata/RHSA-2026:30076
- access.redhat.com/errata/RHSA-2026:33683
- access.redhat.com/errata/RHSA-2026:34160
- access.redhat.com/errata/RHSA-2026:34342
- access.redhat.com/errata/RHSA-2026:34374
- access.redhat.com/errata/RHSA-2026:34766
- access.redhat.com/errata/RHSA-2026:34770
- access.redhat.com/errata/RHSA-2026:36651
Vendor advisories and official records. Exploit/PoC links are deliberately left out.