CVE-2021-21891

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory (severity: CRITICAL) published 2021-12-23. NVD baseline CVSS 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 3%CVSS: 9.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

A stack-based buffer overflow vulnerability exists in the Web Manager FsBrowseClean functionality of Lantronix PremierWave 2050 8.9.0.0R4 (in QEMU). A specially crafted HTTP request can lead to remote code execution in the vulnerable portion of the branch (deletefile). An attacker can make an authenticated HTTP request to trigger this vulnerability.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
47(Track)
EG Risk 47/100SSVC: 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 computed
Severity91% × 45%
Exploitation3% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
85.9%
KEV
Not listed

Published

December 22, 2021

Last Modified

November 21, 2024

Advisory Details (1)

Auto-updated Jul 23, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

TALOS-2021-1334 || Cisco Talos Intelligence Group - Comprehensive Threat Intelligence

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1334

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 46× 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.

  1. 2026-07-23 14:15 UTCEPSS rescore
  2. 2026-07-23 01:57 UTCEG score recompute
  3. 2026-07-22 22:43 UTCEG score recompute
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  68. 2026-05-26 05:57 UTCEG score recompute
  69. 2026-05-26 05:57 UTCGHSA enrichment
  70. 2026-05-25 07:07 UTCOSV refresh
  71. 2026-05-24 16:49 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2021-21891?
CVE-2021-21891 is a critical vulnerability published on December 22, 2021. A stack-based buffer overflow vulnerability exists in the Web Manager FsBrowseClean functionality of Lantronix PremierWave 2050 8.9.0.0R4 (in QEMU). A specially crafted HTTP request can lead to remote code execution in the vulnerable portion of the branch (deletefile). An attacker can make an…
When was CVE-2021-21891 disclosed?
CVE-2021-21891 was first published in the National Vulnerability Database on December 22, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-21891 actively exploited?
CVE-2021-21891 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 85.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-21891?
CVE-2021-21891 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2021-21891?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-21891, 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.

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