CVE-2021-3682

HIGHNVD 8.58.5—
EchelonGraph scoreMEDIUM confidence

Score 8.5 from GitHub Security Advisory (severity: CRITICAL) published 2022-05-24. NVD baseline CVSS 8.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
8.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 3%CVSS: 8.5Exploit: NoneExposed: 0

A fix is available — apply it.

A flaw was found in the USB redirector device emulation of QEMU in versions prior to 6.1.0-rc2. It occurs when dropping packets during a bulk transfer from a SPICE client due to the packet queue being full. A malicious SPICE client could use this flaw to make QEMU call free() with faked heap chunk metadata, resulting in a crash of QEMU or potential code execution with the privileges of the QEMU process on the host.

CVSS v3
8.5
EG Score
8.5(medium)
EPSS
85.5%
KEV
Not listed

Published

August 5, 2021

Last Modified

November 21, 2024

References (12)

Vendor Advisories for CVE-2021-3682(2)

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

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuqemu-system-x86-xen (1:6.0+dfsg-2expubuntu1.2) @ impish2026-05-26ubuntu
ubuntuqemu-system-x86-xen (1:4.2-3ubuntu6.24) @ focal2026-05-26ubuntu
redhatvirt-devel:8.2-8020120210917153657.863bb0db2021-09-30redhat
redhatvirt-devel:av-8040020210922084349.522a0ee42021-09-30redhat

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(1)

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

Additional Vendor Advisories

(3)

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 11× in last 7d / 49× 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 105 total refreshes for this CVE.

  1. 2026-07-22 14:06 UTCEPSS rescore
  2. 2026-07-21 15:22 UTCEPSS rescore
  3. 2026-07-21 15:22 UTCEPSS rescore
  4. 2026-07-20 17:05 UTCEPSS rescore
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  6. 2026-07-19 02:27 UTCEPSS rescore
  7. 2026-07-18 14:59 UTCOSV refresh
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  24. 2026-07-07 13:43 UTCEPSS rescore
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  1. 2026-07-06 16:25 UTCEPSS rescore
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  8. 2026-07-02 16:57 UTCEPSS rescore
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  10. 2026-06-30 23:20 UTCEPSS rescore
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  12. 2026-06-30 20:30 UTCOSV refresh
  13. 2026-06-29 14:04 UTCEPSS rescore
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  17. 2026-06-27 03:06 UTCEPSS rescore
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  21. 2026-06-24 14:03 UTCEPSS rescore
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  23. 2026-06-23 21:31 UTCEPSS rescore
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  25. 2026-06-22 14:24 UTCEPSS rescore
  26. 2026-06-21 01:58 UTCEPSS rescore
  27. 2026-06-21 01:58 UTCEPSS rescore
  28. 2026-06-19 19:24 UTCEPSS rescore
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  30. 2026-06-18 17:51 UTCEPSS rescore
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  37. 2026-06-15 17:46 UTCEPSS rescore
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  40. 2026-06-13 22:58 UTCEPSS rescore
  41. 2026-06-13 22:58 UTCEPSS rescore
  42. 2026-06-13 00:44 UTCOSV refresh
  43. 2026-06-12 23:10 UTCEPSS rescore
  44. 2026-06-11 13:58 UTCEPSS rescore
  45. 2026-06-11 13:58 UTCEPSS rescore
  46. 2026-06-10 22:16 UTCEPSS rescore
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  48. 2026-06-10 13:20 UTCEPSS rescore
  49. 2026-06-08 14:15 UTCEPSS rescore
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  51. 2026-06-07 15:23 UTCEPSS rescore
  52. 2026-06-07 15:23 UTCEPSS rescore
  53. 2026-06-06 13:46 UTCEPSS rescore
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  55. 2026-06-05 22:45 UTCEPSS rescore
  56. 2026-06-05 06:09 UTCEPSS rescore
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  73. 2026-05-26 13:42 UTCEPSS rescore
  74. 2026-05-26 13:42 UTCEPSS rescore
  75. 2026-05-26 12:34 UTCEG score recompute

Frequently asked(5)

What is CVE-2021-3682?
CVE-2021-3682 is a high vulnerability published on August 5, 2021. A flaw was found in the USB redirector device emulation of QEMU in versions prior to 6.1.0-rc2. It occurs when dropping packets during a bulk transfer from a SPICE client due to the packet queue being full. A malicious SPICE client could use this flaw to make QEMU call free() with faked heap chunk…
When was CVE-2021-3682 disclosed?
CVE-2021-3682 was first published in the National Vulnerability Database on August 5, 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-2021-3682 actively exploited?
CVE-2021-3682 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 85.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-3682?
CVE-2021-3682 has a CVSS v3 base score of 8.5 (NVD).
How do I remediate CVE-2021-3682?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-3682, 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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