CVE-2026-33129Public exploitNetwork attack vector

Password recovery via early-exit Basic Auth comparison

Published Mar 20, 2026 · Updated Mar 20, 2026

Timing side channel in requireBasicAuth in UnJS H3 2.0.1-beta.0 through 2.0.1-rc.8 allows remote attackers to recover passwords. The function compares an attacker-supplied Basic Auth password with the configured password using early-exit !==, making correct prefixes measurably slower. No prior privileges or user interaction are required, but repeated concurrent requests and low network jitter are needed to infer credentials character by character.

CVSS severity5.9
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Timing side channel in requireBasicAuth in UnJS H3 2.0.1-beta.0 through 2.0.1-rc.8 allows remote attackers to recover passwords. The function compares an attacker-supplied Basic Auth password with the configured password using early-exit !==, making correct prefixes measurably slower. No prior privileges or user interaction are required, but repeated concurrent requests and low network jitter are needed to infer credentials character by character.

The record

CVE
CVE-2026-33129
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
UnJS
Product
H3
Classifications
CWE-208, T1110.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 2.0.1-beta.0, < 2.0.1-rc.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

UnJS · H3version=>= 2.0.1-beta.0, < 2.0.1-rc.9

Published CVSS scores

5.9GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-208Observable Timing Discrepancy
T1110.001Password Guessing

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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