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CVE Record

CVE-2026-6322: 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.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

fast-uri can change where a URL appears to point after normalization. An attacker-supplied URL may look like it contains an allowed host, but serialize to a different authority. This matters for redirect checks, host allowlists, and outbound routing decisions.

Executive priority

Treat as a high-priority dependency fix where URL validation protects redirects, outbound traffic, or tenant boundaries. Prioritize internet-facing services and security controls relying on host allowlists.

Technical view

In fast-uri versions up to 3.1.1, normalize() decodes percent-encoded authority delimiters inside the host and emits them as raw delimiters. This can reinterpret part of the host as userinfo and make the effective authority become another domain. CVSS is 7.5 high, with integrity impact.

Likely exposure

Exposure is likely in applications that use fast-uri directly or transitively and normalize untrusted URLs before allowlist checks, redirect validation, or server-side outbound request routing.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation. The issue is remotely reachable where attacker-controlled URLs enter affected validation flows and can influence trust decisions.

Researcher notes

The core risk is parser/serializer disagreement around percent-encoded authority delimiters. Evidence supports host confusion, not code execution. Product impact beyond fast-uri and listed vendor advisories should be confirmed from dependency trees and vendor notices.

Mitigation direction

  • Upgrade fast-uri to 3.1.2 or later.
  • Refresh lockfiles and rebuild artifacts that include fast-uri.
  • Check vendor guidance for bundled or transitive copies.
  • Review URL trust decisions using normalized untrusted input.
  • Add regression tests for host and authority consistency.

Validation and detection

  • Search dependency manifests and lockfiles for fast-uri versions up to 3.1.1.
  • Confirm deployed artifacts use fast-uri 3.1.2 or later.
  • Inventory redirect, allowlist, and outbound routing paths using URL normalization.
  • Verify normalized URL authority matches the authority used for policy checks.
  • Review Red Hat advisories if consuming affected Red Hat packages.
Prepared
Confidence
high
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-140: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cwe · low confidence lookup

CWE-436: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2026-6322 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
26Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N3.93.6openjs
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-6322Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPfast-uri: fast-uri: URI authority bypass due to improper delimiter handling
other:Red Hat severity ratingcvssV3_1
  • 2026-05-05T11:01:00.332Z: Reported to Red Hat.
  • 2026-05-05T10:29:16.378Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
fast-urifast-uri0, 3.1.2unaffected
Weakness

CWE details

CWE-140CWE-436

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-140 · source CWE mapping

Improper Neutralization of Delimiters

Improper Neutralization of Delimiters represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-436 · source CWE mapping

Interpretation Conflict

Interpretation Conflict represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs