CVE-2021-21539
Telemetry drift only. No threshold crossed and no authority ruling changed.
CVE record, CISA KEV and EPSS as of 2026-10-18.
CVEs like this one computed, by meaning
What to do now held facts and links
- Upgrade to 4.40.00.00 or later CVE record
- Record your decision, dated and frozen with today's evidence: patch by a date · mitigated by a compensating control · deferred · accepted the risk · not affected
- Check your version against the ranges this record publishes.
What it is stated by the CNA
Dell EMC iDRAC9 versions prior to 4.40.00.00 contain a Time-of-check Time-of-use (TOCTOU) race condition vulnerability. A remote authenticated attacker could potentially exploit this vulnerability to gain elevated privileges when a user with higher privileges is simultaneously accessing iDRAC through the web interface.
- weakness
- Other
- affected
- Dell Integrated Dell Remote Access Controller (iDRAC)
- published ranges
- dell idrac9 firmware < 4.40.00.00
- fixed in
- 4.40.00.00
- severity
- 5.9 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:H/A:L
- assigned by
- dell
- published
- 2021-04-30
check us dell.com
Exploit code held, dated
- exploit code
- None held in the PoC-in-GitHub feed. A public repository changes this brief.
What moved held, dated
| date | EPSS | event |
|---|---|---|
| 1 May 2021 | 0.00556 | |
| 6 Jan 2022 | 0.02445 | |
| 4 Feb 2022 | 0.05246 | |
| 1 Apr 2022 | 0.01055 | |
| 7 Mar 2023 | 0.00148 | scoring model v2023.03.01 |
| 17 Mar 2025 | 0.0043 | scoring model v2025.03.14 |
| 18 Nov 2025 | 0.00496 | |
| 21 Nov 2025 | 0.00415 | |
| 2 May 2026 | 0.00405 | |
| 15 Jun 2026 | 0.00616 | scoring model v2026.06.15 |
17 observations held. A step marked with a scoring model moved because the measurement was replaced, not because the vulnerability changed.
Outside the record researched, cited
This section reads the record's references and adds cited findings from outside it. It needs an account. Everything above is held facts and is complete without it.
What would change this brief held, dated
- CISA KEV
- Not listed in the catalogue we hold. A listing changes this brief.
- exploit probability
- 0.01 on 2026-06-15 (FIRST's EPSS, a probability and not evidence of exploitation). Next band line: 10% (0.10). Crossing a line changes this brief.
- fix
- Held: 4.40.00.00. A newer fix from the CNA or OSV changes this brief.
How to check this
Every value above is held with two dates: when it was true upstream (as_of) and when we recorded it (tx_from). Re-derive the exploit probability as it stood on any date:
SELECT value, source, source_version, as_of, tx_from
FROM volatile_valid_as_of('CVE-2021-21539', '2026-11-02T23:59:59.999999Z', now());