CVE-2021-34337

REST API takeover via timing-based password recovery

Published Apr 15, 2023 · Updated Feb 6, 2025

Observable timing differences in Mailman Core before 3.3.5 allow attackers to recover the REST API password via repeated requests. The REST WSGI middleware compares the submitted Basic Authentication password with admin_pass using short-circuit string equality, leaking matched-prefix length through response timing. The API listens on localhost by default; exposure on another interface lets attackers recover the password and issue arbitrary administrative API calls.

CVSS severity6.3
Medium
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Observable timing differences in Mailman Core before 3.3.5 allow attackers to recover the REST API password via repeated requests. The REST WSGI middleware compares the submitted Basic Authentication password with admin_pass using short-circuit string equality, leaking matched-prefix length through response timing. The API listens on localhost by default; exposure on another interface lets attackers recover the password and issue arbitrary administrative API calls.

The record

CVE
CVE-2021-34337
Published
Apr 15, 2023
Updated
Feb 6, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-208, T1110
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 15, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 6, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.3CISA-ADPCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
6.3NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-208Observable Timing Discrepancy
T1110Brute Force

Public exploit references

No public exploit references are available in this record.

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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