CVE-2021-21266

MEDIUMNVD 6.46.4—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.4 under NVD CVSS v3. EPSS exploit probability: 1.1%, top 38% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
Trending — 3 sources updated this week
6.4
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 6.4Exploit: NoneExposed: 0

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

openHAB is a vendor and technology agnostic open source automation software for your home. In openHAB before versions 2.5.12 and 3.0.1 the XML external entity (XXE) attack allows attackers in the same network as the openHAB instance to retrieve internal information like the content of files from the file system. Responses to SSDP requests can be especially malicious. All add-ons that use SAX or JAXB parsing of externally received XML are potentially subject to this kind of attack. In openHAB, the following add-ons are potentially impacted: AvmFritz, BoseSoundtouch, DenonMarantz, DLinkSmarthome, Enigma2, FmiWeather, FSInternetRadio, Gce, Homematic, HPPrinter, IHC, Insteon, Onkyo, Roku, SamsungTV, Sonos, Roku, Tellstick, TR064, UPnPControl, Vitotronic, Wemo, YamahaReceiver and XPath Tranformation. The vulnerabilities have been fixed in versions 2.5.12 and 3.0.1 by a more strict configuration of the used XML parser.

CVSS v3
6.4
EG Score
6.4(medium)
EG Risk
34(Track)
EG Risk 34/100SSVC: 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
Severity64% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
62.2%
KEV
Not listed

Published

February 1, 2021

Last Modified

November 21, 2024

References (8)

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 50× 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.

Showing the most recent 100 of 103 total refreshes for this CVE.

  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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  73. 2026-05-26 21:28 UTCEG score recompute
  74. 2026-05-26 13:42 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2021-21266?
CVE-2021-21266 is a medium vulnerability published on February 1, 2021. openHAB is a vendor and technology agnostic open source automation software for your home. In openHAB before versions 2.5.12 and 3.0.1 the XML external entity (XXE) attack allows attackers in the same network as the openHAB instance to retrieve internal information like the content of files from…
When was CVE-2021-21266 disclosed?
CVE-2021-21266 was first published in the National Vulnerability Database on February 1, 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-2021-21266 actively exploited?
CVE-2021-21266 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 62.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-21266?
CVE-2021-21266 has a CVSS v3 base score of 6.4 (NVD).
How do I remediate CVE-2021-21266?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-21266, 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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