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Vulnerabilities

Vulnerability · CVE-2026-75899

fast-uri is a URI parser for Node.js.

Published Aug 24, 2026 · catalog updated Oct 15, 2026 · fast-uri is a URI

Check if you run it

No confirmed exploitation is on record for CVE-2026-75899. EPSS is 0.22%. Act only if a listed version of fast-uri is a URI 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 is a URI).
  • 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
0.22%
Remediation
Advisory link
Affected products
Debian:13 node-ajv · Debian:14 node-ajv · cpe openjsf/fast-uri

fast-uri is a URI parser for Node.js. It decodes percent escapes in a hostname during parsing and then decodes the parsed hostname a second time during authority recomposition, so a single call to normalize or resolve can turn nested percent-encoded input into a different network destination such as a loopback hostname or address. For example, a doubly encoded host that spells out a loopback name decodes to that live host in one operation, which contradicts RFC 3986 section 2.4 that an implementation must not decode the same string more than once. An application that normalizes or resolves an untrusted HTTP-family URI before outbound routing, redirect validation, or a host-policy check can receive a destination different from the one the original encoded host represented, giving a server-side request forgery and host-policy bypass primitive. This is an incomplete-fix variant of CVE-2026-6322. The affected versions are 2.4.1 up to but not including 2.4.5, 3.1.2 up to but not including 3.1.6, and 4.0.0 up to but not including 4.1.3. The issue is fixed in 2.4.5, 3.1.6, and 4.1.3, which normalize percent escapes once and preserve encoded percent signs. Users should upgrade to a patched version.

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.

  • Debian:13 node-ajv8.12.0~ds+~2.1.1-5, 8.17.1~ds+~3.0.1+~3.1.0-1, 8.17.1~ds+~3.0.1+~3.1.0-2
  • Debian:14 node-ajv0 → 8.20.0~ds+~cs7.1.4-1
  • cpe openjsf/fast-uriversion unspecified

How to fix CVE-2026-75899

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-2026-75899. EPSS is 0.22%. Act only if a listed version of fast-uri is a URI is installed.

Which versions are affected?

Compare what you have installed with 8.12.0~ds+~2.1.1-5, 8.17.1~ds+~3.0.1+~3.1.0-1, 8.17.1~ds+~3.0.1+~3.1.0-2, 0 → 8.20.0~ds+~cs7.1.4-1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-174; CWE-918: Server-Side Request Forgery (SSRF). EPSS 0.22%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

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

Timeline

Detection, updates, and resolution for this record.

  1. Aug 24, 2026 · NIST NVD

    Detected

    fast-uri is a URI parser for Node.js. It decodes percent escapes in a hostname during parsing and then decodes the parsed hostname a second time during authority recomposition, so a single call to normalize or resolve can turn nested percent-encoded input into a different network destination such as a loopback hostname or address. For example, a doubly encoded host that spells out a loopback name

  2. Oct 14, 2026 · NIST NVD

    Updated

    fast-uri is a URI parser for Node.js. It decodes percent escapes in a hostname during parsing and then decodes the parsed hostname a second time during authority recomposition, so a single call to normalize or resolve can turn nested percent-encoded input into a different network destination such as a loopback hostname or address. For example, a doubly encoded host that spells out a loopback name

  3. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    node-ajv fixed in 8.20.0~ds+~cs7.1.4-1

  4. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    node-ajv fixed in 8.20.0~ds+~cs7.1.4-1

  5. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    fast-uri is a URI parser for Node.js. It decodes percent escapes in a hostname during parsing and then decodes the parsed hostname a second time during authority recomposition, so a single call to normalize or resolve can turn nested percent-encoded input into a different network destination such as a loopback hostname or address. For example, a doubly encoded host that spells out a loopback name

Sources

  • CVE.orgVulnerability recordCVE-2026-75899

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-75899

    30-day exploitation probability 0.2%

    first.org
  • NIST NVDVulnerability recordCVE-2026-75899

    fast-uri is a URI parser for Node.js. It decodes percent escapes in a hostname during parsing and then decodes the parsed hostname a second time during authority recomposition, so a single call to normalize or resolve can turn nested percent-encoded input into a different network

    nvd.nist.gov
  • OpenSSF OSV / OSV ScannerPackage advisoryDEBIAN-CVE-2026-75899
    osv.dev

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.