Security Resilience

CVE-2023-47102

Urbackup Server 2.5.31

Public PoC
Published
07 November 2023
Modified
29 September 2025
CVSS Score v3.1 5.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS Score 0.0063 50th percentile
Risk Priority 45 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). EPSS scores by FIRST (EPSS SIG), generated by Empirical Security. Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-47102 is a medium-severity Observable Discrepancy (CWE-203) vulnerability in Urbackup Server. Its CVSS base score is 5.3 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Brute Force (T1110); ranked at the 50th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability Data

UrBackup Server 2.5.31 allows brute-force enumeration of user accounts because a failure message confirms that a username is not valid.

CWE(s)
CWE-203

Related Threats

MITRE ATT&CK Enterprise Techniques

T1110 Brute Force Credential Access
Adversaries may use brute force techniques to gain access to accounts when passwords are unknown or when password hashes are obtained.
attack.mitre.org →
T1087 Account Discovery Discovery
Adversaries may attempt to get a listing of valid accounts, usernames, or email addresses on a system or within a compromised environment.
attack.mitre.org →
T1558.004 AS-REP Roasting Credential Access
Adversaries may reveal credentials of accounts that have disabled Kerberos preauthentication by [Password Cracking](https://attack.
attack.mitre.org →
T1595 Active Scanning Reconnaissance
Adversaries may execute active reconnaissance scans to gather information that can be used during targeting.
attack.mitre.org →
T1595.001 Scanning IP Blocks Reconnaissance
Adversaries may scan victim IP blocks to gather information that can be used during targeting.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2024-23771Shared CWE-203
CVE-2026-56339Shared CWE-203
CVE-2024-43095Shared CWE-203
CVE-2026-51926Shared CWE-203
CVE-2023-21337Shared CWE-203
CVE-2026-14112Shared CWE-203
CVE-2023-32342Shared CWE-203
CVE-2026-21386Shared CWE-203
CVE-2024-28885Shared CWE-203
CVE-2024-54767Shared CWE-203

Affected Assets

urbackup
urbackup server
2.5.31

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 1 hardening rule · 1 OS baseline
Validate
Prove the fix (OWASP ASVS)

—

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SC-30 Concealment and Misdirection
addresses: CWE-203

Misdirection can normalize or falsify responses to eliminate observable discrepancies that aid reconnaissance.

SC-31 Covert Channel Analysis
addresses: CWE-203

Observable discrepancies in system behavior can be modulated to create covert storage or timing channels; the required analysis detects and constrains such avenues.

SI-11 Error Handling
addresses: CWE-203

Prevents attackers from using observable differences in error responses to infer internal system details or state.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
blocks

Secure SDLC practices directly prevent observable response discrepancies via consistent error handling and timing.

References