CVE-2026-6321 — fast-uri
HIGHCVE-2026-6321 is a high-severity (CVSS 7.5) Path Traversal vulnerability in fast-uri. A fix is available for fast-uri — see the affected versions and patch details below.
fast-uri vulnerable to path traversal via percent-encoded dot segments
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-6321.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-6321 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
fast-urinpmDescription
Impact
fast-uri v3.1.0 and earlier decodes percent-encoded path separators (%2F) and dot segments (%2E) before applying dot-segment removal in normalize() and equal(). This makes encoded path data behave like real / and .., so distinct URIs collapse onto the same normalized path.
For example, http://example.com/public/%2e%2e/admin normalizes to http://example.com/admin, and equal() considers them the same URI.
Applications that normalize or compare attacker-controlled URLs to enforce path-based policy can be bypassed. A path that looks confined under an allowed prefix can normalize to a different location.
Patches
Upgrade to fast-uri >= 3.1.1, or if you are in the v2.x release line, v2.4.1
Workarounds
None. Upgrade to the patched version.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | fast-uri | ≥ 3.0.0&&< 3.1.1 | 3.1.1npm install fast-uri@3.1.1 |
| 📦npm | fast-uri | all versions | 2.4.1npm install fast-uri@2.4.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fast-uri, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update fast-uri to 3.1.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-6321 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-6321 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-6321. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| HawtIO HawtIO 4.4.0 | io.hawt-project | RHSA-2026:25089 |
| Red Hat Ansible Automation Platform 2.5 for RHEL 8 | automation-gateway-0:2.5.20260715-1.el8ap | RHSA-2026:42078 |
| Red Hat Ansible Automation Platform 2.6 for RHEL 9 | automation-platform-ui-0:2.6.11-1.el9ap | RHSA-2026:42079 |
| Red Hat Enterprise Linux 10 | rh-podman-desktop-0:1.1.1-1.el10_2 | RHSA-2026:37385 |
| Cluster Observability Operator 1.5.0 | cluster-observability-operator/distributed-tracing-console-plugin-pf4-rhel9:1782840519 | RHSA-2026:34342 |
| Network Observability (NETOBSERV) 1.12.3 | network-observability/network-observability-console-plugin-rhel9:1780556069 | RHSA-2026:24473 |
| Red Hat Ansible Automation Platform 2.5 | ansible-automation-platform-25/lightspeed-rhel8:1780082949 | RHSA-2026:24766 |
| Red Hat Ansible Automation Platform 2.6 | ansible-automation-platform-26/lightspeed-rhel9:1779784904 | RHSA-2026:24866 |
Frequently Asked Questions
Is CVE-2026-6321 in your dependencies?
O3 Security finds CVE-2026-6321 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.