Raw vector
CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:HSummary
CVE-2026-20138 is a medium-severity Insertion of Sensitive Information into Log File (CWE-532) vulnerability in Splunk Splunk. Its CVSS base score is 6.8 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Unsecured Credentials (T1552); ranked at the 23th 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-6 (Least Privilege) and AU-9 (Protection of Audit Information) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-7935
Vulnerability Data
In Splunk Enterprise versions below 10.2.0, 10.0.2, 9.4.7, 9.3.9, and 9.2.11, a user of a Splunk Search Head Cluster (SHC) deployment who holds a role with access to the Splunk `_internal` index could view the `integrationKey`, `secretKey`, and `appSecretKey` secrets,…
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generated by [Duo Two-Factor Authentication for Splunk Enterprise](https://duo.com/docs/splunk), in plain text.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Vulnerability exposes Duo 2FA secrets in plain text via _internal index (CWE-532), directly enabling unsecured credential access.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Directly protects audit/internal log contents (the _internal index) from unauthorized access or exposure of sensitive values such as secret keys.
Enforces least-privilege restrictions so that only authorized roles can access the _internal index or the Duo integration secrets stored within it.
Requires protection of sensitive information (the plaintext secret keys) at rest inside Splunk indexes or configuration stores.
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.
Secure SDLC practices directly prohibit writing sensitive data to logs; eliminating the weakness satisfies only one narrow slice of the control.
Log generation configuration can and should exclude sensitive data, but the control statement focuses on availability rather than content filtering.
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.
Requiring de-identification and privacy controls before logs leave the organization reduces the chance that sensitive data inadvertently captured in logs becomes exposed to external parties.
By defining what records must be kept, where, and for how long, the control discourages the inadvertent inclusion of sensitive information in logs or other externally accessible files that fall outside the formal record system.
Mandating deletion of temporary files and logs that may contain sensitive information prevents those artifacts from remaining accessible after the data is no longer needed.
When log entries are produced from masked data sets, the control prevents the inadvertent insertion of sensitive values into externally accessible log files.
DLP inspection of logs and file transfers can detect and block the inadvertent placement of sensitive tokens or credentials into externally accessible log files before they are written or transmitted.
Requiring restrictions on free-text fields and proper error-message handling stops developers from embedding or leaking sensitive data into logs or diagnostic output.