HCL BigFix Service Management is affected by an Administrative Session Concurrency vulnerability. The application allows multiple simultaneous authenticated sessions for the same administrative account, which could enable an unauthorized attacker to predict or hijack valid session identifiers. Successful exploitation allows an attacker to compromise affected administrative sessions and execute actions with full privileged user permissions.
CVE-2026-21806
LOWPre-NVD 3.13.1—Trending — 3 sources updated this week
EchelonGraph scoreHIGH confidence
Score 3.1 from GitHub Security Advisory (severity: LOW) published 2026-09-18. a secondary CVSS source baseline 3.1; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: ghsa, secondary
3.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: —CVSS: 3.1Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 3.1
- EG Score
- 3.1(high)
- EG Risk
- 14(Track)EG Risk 14/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity31% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- —
- EPSS %ILE
- —
- KEV
- Not listed
Published
September 18, 2026
Last Modified
September 18, 2026
References (1)
Vendor Advisories for CVE-2026-21806(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 9× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-09-18 20:31 UTCEG score recompute
- 2026-09-18 20:31 UTCGHSA enrichment
- 2026-09-18 19:19 UTCEG score recompute
- 2026-09-18 19:19 UTCGHSA enrichment
- 2026-09-18 14:00 UTCEG score recompute
- 2026-09-18 14:00 UTCGHSA enrichment
- 2026-09-18 12:21 UTCEG score recompute
- 2026-09-18 11:19 UTCEG score recompute
- 2026-09-18 11:19 UTCMITRE cvelistV5first tracked
Frequently asked(4)
What is CVE-2026-21806?
CVE-2026-21806 is a low vulnerability published on September 18, 2026. HCL BigFix Service Management is affected by an Administrative Session Concurrency vulnerability. The application allows multiple simultaneous authenticated sessions for the same administrative account, which could enable an unauthorized attacker to predict or hijack valid session identifiers.…
When was CVE-2026-21806 disclosed?
CVE-2026-21806 was first published in the National Vulnerability Database on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-21806?
CVE-2026-21806 has a CVSS v3 base score of 3.1 (NVD).
How do I remediate CVE-2026-21806?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-21806, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-21806
Is Your Infrastructure Affected by CVE-2026-21806?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.