fast-uri: Interpretation Conflict
CVE-2026-6322 is a high-severity interpretation conflict vulnerability in fast-uri, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 3.1.2 as the first without the flaw, so updating fast-uri to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.51% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update fast-uri to 3.1.2 or a later version.
- Read the advisory on cna.openjsf.org for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE; 31 further products are omitted here. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N. Scored by CNA.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | CNA |
| CVSS 3.1 | 7.5 | High | CNA |
Official description
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Interpretation Conflict
Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other references
- 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
Other vulnerabilities in fast-uri
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
Recent Interpretation Conflict vulnerabilities
- 9.1 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
- 7.5 High severity
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