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Vulnerabilities

Vulnerability · CVE-2026-6321

fast-uri decoded percent-encoded path separators and dot segments before applying dot-segment removal in its normalize() and equal() functions.

Published May 4, 2026 · catalog updated Sep 10, 2026 · fast-uri decoded percent-encoded path

Check if you run it

No confirmed exploitation is on record for CVE-2026-6321. EPSS is 0.77%. Act only if a listed version of fast-uri decoded percent-encoded path is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (fast-uri decoded percent-encoded path).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.77%
Remediation
Version ranges on file
Affected products
cpe openjsf/fast-uri · stated fast-uri

fast-uri decoded percent-encoded path separators and dot segments before applying dot-segment removal in its normalize() and equal() functions. Encoded path data was treated like real slashes and parent-directory references, so distinct URIs could collapse onto the same normalized path. Applications that normalize or compare attacker-controlled URLs to enforce path-based policy can be bypassed, with a path that appears confined under an allowed prefix normalizing to a different location. Versions <= 3.1.0 are affected. Update to 3.1.1 or later.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe openjsf/fast-uriversion unspecified
  • stated fast-uri<= 3.1.0

How to fix CVE-2026-6321

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-6321. EPSS is 0.77%. Act only if a listed version of fast-uri decoded percent-encoded path is installed.

Which versions are affected?

Compare what you have installed with <= 3.1.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-22: Path Traversal. EPSS 0.77%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 4, 2026 · NIST NVD

    Detected

    fast-uri decoded percent-encoded path separators and dot segments before applying dot-segment removal in its normalize() and equal() functions. Encoded path data was treated like real slashes and parent-directory references, so distinct URIs could collapse onto the same normalized path. Applications that normalize or compare attacker-controlled URLs to enforce path-based policy can be bypassed, wi

  2. Sep 10, 2026 · NIST NVD

    Updated

    fast-uri decoded percent-encoded path separators and dot segments before applying dot-segment removal in its normalize() and equal() functions. Encoded path data was treated like real slashes and parent-directory references, so distinct URIs could collapse onto the same normalized path. Applications that normalize or compare attacker-controlled URLs to enforce path-based policy can be bypassed, wi

Sources

  • CVE.orgVulnerability recordCVE-2026-6321

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-6321

    30-day exploitation probability 0.8%

    first.org
  • NIST NVDVulnerability recordCVE-2026-6321

    fast-uri decoded percent-encoded path separators and dot segments before applying dot-segment removal in its normalize() and equal() functions. Encoded path data was treated like real slashes and parent-directory references, so distinct URIs could collapse onto the same normalize

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.