Security readout for executives and security teams
Plain-English summary
CVE-2018-9275 is a flaw in Yubico's PAM module where successful logins can leave a file handle open. Over time, this may expose a YubiKey device serial number from the auth mapping file or degrade login service availability by exhausting file descriptors.
Executive priority
Treat this as a targeted authentication infrastructure maintenance issue, not an emergency internet-wide exposure. Prioritize hosts that use YubiKey-backed PAM login and have high login volume or strict availability requirements.
Technical view
In pam_yubico 2.18 through 2.25, check_user_token in util.c can leak file descriptors to the auth mapping file after successful authentication. The documented impacts are information disclosure of a device serial number and denial of service from reaching the process file-descriptor limit.
Likely exposure
Exposure is limited to systems using the Yubico PAM module, pam_yubico, versions 2.18 through 2.25. The bundle does not identify broader products, CPEs, or downstream distribution package names.
Exploitation context
The source bundle does not show active exploitation, public exploit details, or CISA KEV listing. The condition described occurs after successful logins, so practical risk depends on PAM deployment, login volume, and file-descriptor limits.
Researcher notes
Evidence is clear on affected component, version range, vulnerable function, and impact class. The bundle lacks CVSS, CWE, detailed distribution advisory status, and exploit evidence, so validation should focus on deployed pam_yubico versions and whether the referenced fix is present.
Mitigation direction
- Upgrade pam_yubico beyond the affected 2.18 through 2.25 range if vendor guidance confirms the fix.
- Apply downstream Linux distribution security updates for pam_yubico where available.
- Review Yubico issue and commit references for the specific file-descriptor leak fix.
- Monitor authentication services for abnormal file-descriptor growth after logins.
Validation and detection
- Inventory systems using pam_yubico and record installed package versions.
- Check PAM configuration for active pam_yubico use on login paths.
- Confirm whether vendor packages include Yubico commit 0f6ceabab0a8849b47f67d727aa526c2656089ba.
- Review logs or process metrics for file-descriptor exhaustion symptoms in authentication services.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2018-9275 mapping review
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Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.opensuse.org/show_bug.cgi?id=1088027CVE reference · x_refsource_CONFIRM
- https://github.com/Yubico/yubico-pam/commit/0f6ceabab0a8849b47f67d727aa526c2656089baCVE reference · x_refsource_CONFIRM
- https://github.com/Yubico/yubico-pam/issues/136CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.