CVE-2023-25806Network attack vector

Username enumeration via unequal password-hash work

Published Mar 2, 2023 · Updated Mar 5, 2025

Observable timing discrepancy in OpenSearch Security before 1.3.9 and 2.0.0 through 2.5.0 allows remote attackers to enumerate valid usernames. InternalAuthenticationBackend.authenticate returned before performing bcrypt work for an absent username, while an existing username triggered password-hash verification. The oracle is reachable without authentication only when the internal basic identity provider is enabled, and it discloses account existence without exposing passwords or changing data.

CVSS severity5.3
Medium
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Observable timing discrepancy in OpenSearch Security before 1.3.9 and 2.0.0 through 2.5.0 allows remote attackers to enumerate valid usernames. InternalAuthenticationBackend.authenticate returned before performing bcrypt work for an absent username, while an existing username triggered password-hash verification. The oracle is reachable without authentication only when the internal basic identity provider is enabled, and it discloses account existence without exposing passwords or changing data.

The record

CVE
CVE-2023-25806
Published
Mar 2, 2023
Updated
Mar 5, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-208, CWE-203, T1087
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 2, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 5, 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 vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3GitHubCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-208Observable Timing Discrepancy
CWE-203Observable Discrepancy
T1087Account Discovery

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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