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Vulnerabilities

Vulnerability · CVE-2026-33490

H3 is a minimal H(TTP) framework.

Published Mar 26, 2026 · catalog updated Jun 17, 2026 · H3 is a minimal

Check if you run it

No confirmed exploitation is on record for CVE-2026-33490. EPSS is 0.28%. Act only if a listed version of H3 is a minimal is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (H3 is a minimal).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.28%
Remediation
Advisory link
Affected products
cpe h3/h3

H3 is a minimal H(TTP) framework. In versions 2.0.0-0 through 2.0.1-rc.16, the method in h3 uses a simple check to determine whether incoming requests fall under a mounted sub-application's path prefix. Because this check does not verify a path segment boundary (i.e., that the next character after the base is or end-of-string), middleware registered on a mount like will also execute for unrelated routes such as , , or . This allows an attacker to trigger context-setting middleware on paths it was never intended to cover, potentially polluting request context with unintended privilege flags. Version 2.0.2-rc.17 contains a patch.

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 h3/h32.0.1

How to fix CVE-2026-33490

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-2026-33490. EPSS is 0.28%. Act only if a listed version of H3 is a minimal is installed.

Which versions are affected?

Compare what you have installed with 2.0.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-706. EPSS 0.28%. 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.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 26, 2026 · NIST NVD

    Detected

    H3 is a minimal H(TTP) framework. In versions 2.0.0-0 through 2.0.1-rc.16, the method in h3 uses a simple check to determine whether incoming requests fall under a mounted sub-application's path prefix. Because this check does not verify a path segment boundary (i.e., that the next character after the base is or end-of-string), middleware registered on a mount like will also execute for unrelated

  2. Jun 17, 2026 · NIST NVD

    Updated

    H3 is a minimal H(TTP) framework. In versions 2.0.0-0 through 2.0.1-rc.16, the method in h3 uses a simple check to determine whether incoming requests fall under a mounted sub-application's path prefix. Because this check does not verify a path segment boundary (i.e., that the next character after the base is or end-of-string), middleware registered on a mount like will also execute for unrelated

Sources

  • CVE.orgVulnerability recordCVE-2026-33490

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-33490

    30-day exploitation probability 0.3%

    first.org
  • NIST NVDVulnerability recordCVE-2026-33490

    H3 is a minimal H(TTP) framework. In versions 2.0.0-0 through 2.0.1-rc.16, the method in h3 uses a simple check to determine whether incoming requests fall under a mounted sub-application's path prefix. Because this check does not verify a path segment bo

    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.