Cyber Resilience

CVE-2026-23901

Apache Shiro ≤ 2.0.7

Published
10 February 2026
Modified
12 February 2026
CVSS Score v4 1.0
Click a component to see what it means
Raw vectorCVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:A/VC:L/VI:N/VA:N/SC:L/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:N/AU:Y/R:A/V:C/RE:L/U:Green
EPSS Score 0.0022 13th percentile
Risk Priority 15 floored blend · peak EPSS

Summary

CVE-2026-23901 is a low-severity Observable Timing Discrepancy (CWE-208) vulnerability in Apache Shiro. Its CVSS base score is 1.0 (Low).

Operationally, exploitation aligns with the MITRE ATT&CK technique Brute Force (T1110); ranked at the 13th 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-7 (Unsuccessful Logon Attempts) and SC-7 (Boundary Protection) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

Observable Timing Discrepancy vulnerability in Apache Shiro. This issue affects Apache Shiro: from 1.*, 2.* before 2.0.7. Users are recommended to upgrade to version 2.0.7 or later, which fixes the issue. Prior to Shiro 2.0.7, code paths for non-existent vs.…

more

existing users are different enough, that a brute-force attack may be able to tell, by timing the requests only, determine if the request failed because of a non-existent user vs. wrong password. The most likely attack vector is a local attack only. Shiro security model https://shiro.apache.org/security-model.html#username_enumeration discusses this as well. Typically, brute force attack can be mitigated at the infrastructure level.

CWE(s)
CWE-208

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

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 →
T1110.001 Password Guessing Credential Access
Adversaries with no prior knowledge of legitimate credentials within the system or environment may guess passwords to attempt access to accounts.
attack.mitre.org →
Why these techniques?

Timing side-channel enables username enumeration to improve effectiveness of password guessing/brute force attacks against the auth system.

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

CVEs Like This One

CVE-2026-49268Same product: Apache Shiro
CVE-2026-43827Same product: Apache Shiro
CVE-2026-43828Same product: Apache Shiro
CVE-2026-48589Same product: Apache Shiro
CVE-2023-46749Same product: Apache Shiro
CVE-2026-44598Same product: Apache Shiro
CVE-2023-46750Same product: Apache Shiro
CVE-2023-34478Same product: Apache Shiro
CVE-2020-17523Same product: Apache Shiro
CVE-2026-23903Same product: Apache Shiro

Affected Assets

apache
shiro
≤ 2.0.7

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • AC-7 Unsuccessful Logon Attempts
  • SC-7 Boundary Protection
Detect
Catch it (NIST detect / respond)
  • SI-4 System Monitoring
Harden
Shrink the surface (DISA STIG)

—

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

Mitigating Controls (NIST 800-53 r5) AI

AC-7 Unsuccessful Logon Attempts good match
prevent

Limits repeated authentication attempts, directly blocking the brute-force timing enumeration of user existence described in the CVE.

SC-7 Boundary Protection partial match
prevent

Enforces perimeter rate-limiting and traffic analysis that can stop high-volume timing probes against the Shiro login path.

SI-4 System Monitoring partial match
detect

Enables monitoring of authentication timing patterns and login failure distributions that reveal the observable timing discrepancy.

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