h3 has an observable timing discrepancy in basic auth utils
Priority MEDIUM 60CWE-208Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-208.
Summary
H3 is a minimal H(TTP) framework. Versions 2.0.1-beta.0 through 2.0.0-rc.8 contain a Timing Side-Channel vulnerability in the requireBasicAuth function due to the use of unsafe string comparison (!==). This allows an attacker to deduce the valid password character-by-character by measuring the server's response time, effectively bypassing password complexity protections. This issue is fixed in version 2.0.1-rc.9.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00332 26th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed h3 (h3js): 2.0.1-rc.9h3 (npm): 2.0.1-rc.9
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| h3js | h3 | 2.0.1-beta.0 to before 2.0.1-rc.9 | 2.0.1-rc.9 | Patch available | CNA |
| — | h3 (npm) | 2.0.0-beta.0 to before 2.0.1-rc.9 | 2.0.1-rc.9 | Patch available | GHSA-26f5-8h2x-34xh |
- h3 Vendorh3js Affected 2.0.1-beta.0 to before 2.0.1-rc.9 Fixed in 2.0.1-rc.9 Patch available CNA
- h3 (npm) Vendor— Affected 2.0.0-beta.0 to before 2.0.1-rc.9 Fixed in 2.0.1-rc.9 Patch available GHSA-26f5-8h2x-34xh
CPE configurations NVD · 9
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:h3:h3:2.0.0:*:*:*:*:node.js:*:* | 2.0.0 | Vulnerable | h3js |
| cpe:2.3:a:h3:h3:2.0.1:rc1:*:*:*:node.js:*:* | 2.0.1 rc1 | Vulnerable | h3js |
| cpe:2.3:a:h3:h3:2.0.1:rc2:*:*:*:node.js:*:* | 2.0.1 rc2 | Vulnerable | h3js |
| cpe:2.3:a:h3:h3:2.0.1:rc3:*:*:*:node.js:*:* | 2.0.1 rc3 | Vulnerable | h3js |
| cpe:2.3:a:h3:h3:2.0.1:rc4:*:*:*:node.js:*:* | 2.0.1 rc4 | Vulnerable | h3js |
| cpe:2.3:a:h3:h3:2.0.1:rc5:*:*:*:node.js:*:* | 2.0.1 rc5 | Vulnerable | h3js |
| cpe:2.3:a:h3:h3:2.0.1:rc6:*:*:*:node.js:*:* | 2.0.1 rc6 | Vulnerable | h3js |
| cpe:2.3:a:h3:h3:2.0.1:rc7:*:*:*:node.js:*:* | 2.0.1 rc7 | Vulnerable | h3js |
| cpe:2.3:a:h3:h3:2.0.1:rc8:*:*:*:node.js:*:* | 2.0.1 rc8 | Vulnerable | h3js |
- cpe:2.3:a:h3:h3:2.0.0:*:*:*:*:node.js:*:* Versions 2.0.0 Vulnerable ·h3js
- cpe:2.3:a:h3:h3:2.0.1:rc1:*:*:*:node.js:*:* Versions 2.0.1 rc1 Vulnerable ·h3js
- cpe:2.3:a:h3:h3:2.0.1:rc2:*:*:*:node.js:*:* Versions 2.0.1 rc2 Vulnerable ·h3js
- cpe:2.3:a:h3:h3:2.0.1:rc3:*:*:*:node.js:*:* Versions 2.0.1 rc3 Vulnerable ·h3js
- cpe:2.3:a:h3:h3:2.0.1:rc4:*:*:*:node.js:*:* Versions 2.0.1 rc4 Vulnerable ·h3js
- cpe:2.3:a:h3:h3:2.0.1:rc5:*:*:*:node.js:*:* Versions 2.0.1 rc5 Vulnerable ·h3js
- cpe:2.3:a:h3:h3:2.0.1:rc6:*:*:*:node.js:*:* Versions 2.0.1 rc6 Vulnerable ·h3js
- cpe:2.3:a:h3:h3:2.0.1:rc7:*:*:*:node.js:*:* Versions 2.0.1 rc7 Vulnerable ·h3js
- cpe:2.3:a:h3:h3:2.0.1:rc8:*:*:*:node.js:*:* Versions 2.0.1 rc8 Vulnerable ·h3js
Remediation
- Fix · CNA h3 (h3js) Fixed in 2.0.1-rc.9
- Fix · GHSA-26f5-8h2x-34xh h3 (npm) Fixed in 2.0.1-rc.9 Advisory →
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2026-33129
- 2026-10-03 Alias added: GHSA-26f5-8h2x-34xh
References
More h3js H3 vulnerabilities
- TI-2026-25559 h3 has a Server-Sent Events Injection via Unsanitized Newlines in Event Stream Fields CVSS 3.1CRITICAL 10.0
- TI-2026-25562 h3 has a middleware bypass with one gadget CVSS 3.1CRITICAL 9.1
- TI-2026-25886 h3: Missing Path Segment Boundary Check in `mount()` Causes Middleware Execution on Unrelated Prefix-Matching Routes CVSS 3.1MEDIUM 5.3
- TI-2026-18951 h3 v1 has Request Smuggling (TE.TE) issue CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-33129 · CVE Program
- CVE-2026-33129 · NVD
- FIRST EPSS
- GHSA-26f5-8h2x-34xh · GitHub Advisory Database · CC BY 4.0
- CVE-2026-33129 · Red Hat security data · CC BY 4.0
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