CVE-2021-4207

HIGHNVD 8.28.8▲
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2022-04-30. NVD baseline CVSS 8.2; sources differ by 0.6.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
8.2
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 8.2Exploit: NoneExposed: 0

A fix is available — apply it.

A flaw was found in the QXL display device emulation in QEMU. A double fetch of guest controlled values cursor->header.width and cursor->header.height can lead to the allocation of a small cursor object followed by a subsequent heap-based buffer overflow. A malicious privileged guest user could use this flaw to crash the QEMU process on the host or potentially execute arbitrary code within the context of the QEMU process.

CVSS v3
8.2
EG Score
8.8(medium)
EG Risk
44(Track)
EG Risk 44/100SSVC: 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
Severity88% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
32.4%
KEV
Not listed

Published

April 29, 2022

Last Modified

March 21, 2025

References (11)

Vendor Advisories for CVE-2021-4207(3)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuqemu-system-x86-xen (1:4.2-3ubuntu6.23) @ focal2026-05-25ubuntu
redhatvirt:rhel-8060020220616155742.ad008a3a2022-08-02redhat
redhatvirt-devel:av-8040020220517095834.522a0ee42022-06-13redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(2)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 13× 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 102 total refreshes for this CVE.

  1. 2026-07-23 02:04 UTCEG score recompute
  2. 2026-07-22 22:51 UTCEG score recompute
  3. 2026-07-22 14:06 UTCEPSS rescore
  4. 2026-07-21 15:22 UTCEPSS rescore
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  11. 2026-07-17 13:59 UTCOSV refresh
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  30. 2026-06-19 19:24 UTCEPSS rescore
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  43. 2026-06-12 03:27 UTCOSV refresh
  44. 2026-06-11 13:58 UTCEPSS rescore
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  74. 2026-05-25 23:02 UTCEG score recompute
  75. 2026-05-25 23:02 UTCVendor advisory

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Frequently asked(5)

What is CVE-2021-4207?
CVE-2021-4207 is a high vulnerability published on April 29, 2022. A flaw was found in the QXL display device emulation in QEMU. A double fetch of guest controlled values cursor->header.width and cursor->header.height can lead to the allocation of a small cursor object followed by a subsequent heap-based buffer overflow. A malicious privileged guest user could use…
When was CVE-2021-4207 disclosed?
CVE-2021-4207 was first published in the National Vulnerability Database on April 29, 2022, with the most recent update on March 21, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-4207 actively exploited?
CVE-2021-4207 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 32.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-4207?
CVE-2021-4207 has a CVSS v3 base score of 8.2 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.8.
How do I remediate CVE-2021-4207?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-4207, 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

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