Cyber Resilience

CVE-2026-41161

Sync-In Server ≤ 2.2.0

Published
08 May 2026
Modified
17 June 2026
Patch / advisory
View advisory
CVSS Score v4 6.9
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0033 26th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-41161 is a medium-severity Observable Timing Discrepancy (CWE-208) vulnerability in Sync-In Sync-In Server. Its CVSS base score is 6.9 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Account Discovery (T1087); ranked at the 26th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and IA-6 (Authentication Feedback) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

Sync-in Server is a secure, open-source platform for file storage, sharing, collaboration, and syncing. Prior to version 2.2.0, the /api/auth/login endpoint contains a logic flaw that allows unauthenticated remote attackers to enumerate valid usernames by measuring the application's response time.…

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This issue has been patched in version 2.2.0.

CWE(s)
CWE-208

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

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 →
Why these techniques?

Timing-based username enumeration on auth endpoint directly enables account discovery (T1087).

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2025-67438Same product: Sync-In Sync-In Server
CVE-2025-56869Same product: Sync-In Sync-In Server
CVE-2026-41263Shared CWE-208
CVE-2026-21840Shared CWE-208
CVE-2026-48011Shared CWE-208
CVE-2026-41418Shared CWE-208
CVE-2026-32702Shared CWE-208
CVE-2026-40263Shared CWE-208
CVE-2026-54685Shared CWE-208
CVE-2026-48859Shared CWE-208

Affected Assets

sync-in
sync-in server
≤ 2.2.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • AC-3 Access Enforcement
  • IA-6 Authentication Feedback
  • SI-10 Information Input Validation
Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V11.2.4

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match
prevent

Directly enforces uniform authentication outcomes at the login endpoint so that response timing cannot distinguish valid usernames.

IA-6 Authentication Feedback good match
prevent

Requires obscuring all authentication feedback, including side-channel timing differences that enable username enumeration.

SI-10 Information Input Validation partial match
prevent

Mandates consistent validation and error handling for authentication inputs, eliminating observable timing variations between valid and invalid usernames.

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
prevents

Secure SDLC practices directly require constant-time implementations that eliminate observable timing discrepancies.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

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

A.8.17 Clock synchronization none match
none

Consistent reference clocks limit the attacker's ability to measure or manipulate timing differences that could reveal internal state or processing paths.

References