CVE-2026-18446: fast-uri before 4.1.2, 3.1.5, and 2.4.4 requires a literal double forward slash to recognize a URI authority,

Q: How do I fix CVE-2026-18446?

fast-uri: upgrade to 2.4.4, 3.1.5, 4.1.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-18446 being exploited?

CVE-2026-18446 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-18446 affect?

CVE-2026-18446 affects fast-uri. Severity is high (CVSS 7.5). fast-uri before 4.1.2, 3.1.5, and 2.4.4 requires a literal double forward slash to recognize a URI authority, so a reference that uses a backslash based introducer in place of it (backslash backslash, forward slash backslash, or backslash f

Q: How urgent is CVE-2026-18446?

Priority 39/100. High severity; Remotely exploitable, no login, no user action

Routine

HIGH 7.5REMOTEUPGRADE

CVE-2026-18446 is a high-severity flaw (CVSS 7.5) affecting fast-uri. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

fast-uri before 4.1.2, 3.1.5, and 2.4.4 requires a literal double forward slash to recognize a URI authority, so a reference that uses a backslash based introducer in place of it (backslash backslash, forward slash backslash, or backslash forward slash) is parsed with no authority and folds into the path. Node's native WHATWG URL parser instead treats a backslash as interchangeable with a forward slash for special schemes, so the two parsers extr

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 68%)
CISA exploited list	No
Weakness	CWE-436
Published	2026-07-31
Last modified	2026-09-02

Publisher (CNA): openjs · Vendor: openjsf

Last updated 2026-09-02 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-31 15:16 UTCPublished CVE record published
2026-09-02 14:42 UTCUpdated Record last modified

openjsf fast-uri UPGRADE

Affected: < 2.4.4 · >= 3.0.0 and < 3.1.5 · >= 4.0.0 and < 4.1.2

Fixed in: 2.4.4, 3.1.5, 4.1.2

Safe to downgrade to: a release before 3.0.0

1. Check installed version

npm ls fast-uri

2. UPGRADE to 2.4.4

npm install fast-uri@">=2.4.4"

3. If no update is available yet, DOWNGRADE to a release before 3.0.0

npm view fast-uri versions npm install fast-uri@"<3.0.0"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-18446?

fast-uri: upgrade to 2.4.4, 3.1.5, 4.1.2. Exact commands for each OS are on this page.

Is CVE-2026-18446 being exploited?

CVE-2026-18446 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-18446 affect?

CVE-2026-18446 affects fast-uri. Severity is high (CVSS 7.5). fast-uri before 4.1.2, 3.1.5, and 2.4.4 requires a literal double forward slash to recognize a URI authority, so a reference that uses a backslash based introducer in place of it (backslash backslash, forward slash backslash, or backslash f

How urgent is CVE-2026-18446?

Priority 39/100. High severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-75931 HIGH 7.5 UPGRADE fast-uri is a URI parser for Node.js
CVE-2026-76172 HIGH 7.5 UPGRADE fast-uri is a URI parser for Node.js
CVE-2026-75899 HIGH 7.5 UPGRADE fast-uri is a URI parser for Node.js
CVE-2026-75975 HIGH 7.5 UPGRADE fast-uri is a URI parser for Node.js
CVE-2026-84292 HIGH 7.5 UPGRADE fast-uri serializes the port component of a URI without validating it

References

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