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Vulnerabilities

Vulnerability · CVE-2026-76172

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-2026-76172. EPSS is 0.23%. 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
0.23%
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. During parsing it runs a legacy decoding pass over the scheme component and never re-escapes the result, and serialization writes the scheme back out verbatim, unlike the host component which is re-escaped. As a result an input whose scheme carries percent-encoded slashes parses as a scheme with no authority, so the parsed host and error are both undefined, yet resolving or normalizing that same input emits a network-path reference whose authority is attacker-chosen and re-parses to that host. An application that allowlists on the parsed host, or treats a reference with no authority as safe to resolve against its base, gets the opposite of what it checked, giving an off-site redirect, server-side request forgery, or address-policy bypass. The legacy decoder also expands non-standard escape forms, widening the issue past upstream filters, and control characters in the scheme can reach the output as raw carriage return and line feed. The affected versions are 2.3.1 up to but not including 2.4.5, 3.0.0 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 reject a scheme that is not valid after decoding. 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-2026-76172

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-2026-76172. EPSS is 0.23%. 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-177. EPSS 0.23%. 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. During parsing it runs a legacy decoding pass over the scheme component and never re-escapes the result, and serialization writes the scheme back out verbatim, unlike the host component which is re-escaped. As a result an input whose scheme carries percent-encoded slashes parses as a scheme with no authority, so the parsed host and error are both undefined, ye

  2. Oct 14, 2026 · NIST NVD

    Updated

    fast-uri is a URI parser for Node.js. During parsing it runs a legacy decoding pass over the scheme component and never re-escapes the result, and serialization writes the scheme back out verbatim, unlike the host component which is re-escaped. As a result an input whose scheme carries percent-encoded slashes parses as a scheme with no authority, so the parsed host and error are both undefined, ye

  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. During parsing it runs a legacy decoding pass over the scheme component and never re-escapes the result, and serialization writes the scheme back out verbatim, unlike the host component which is re-escaped. As a result an input whose scheme carries percent-encoded slashes parses as a scheme with no authority, so the parsed host and error are both undefined, ye

Sources

  • CVE.orgVulnerability recordCVE-2026-76172

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-76172

    30-day exploitation probability 0.2%

    first.org
  • NIST NVDVulnerability recordCVE-2026-76172

    fast-uri is a URI parser for Node.js. During parsing it runs a legacy decoding pass over the scheme component and never re-escapes the result, and serialization writes the scheme back out verbatim, unlike the host component which is re-escaped. As a result an input whose scheme c

    nvd.nist.gov
  • OpenSSF OSV / OSV ScannerPackage advisoryDEBIAN-CVE-2026-76172
    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.