CVE-2021-3527

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 3 sources updated this week
5.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.5Exploit: NoneExposed: 0

A fix is available — apply it.

A flaw was found in the USB redirector device (usb-redir) of QEMU. Small USB packets are combined into a single, large transfer request, to reduce the overhead and improve performance. The combined size of the bulk transfer is used to dynamically allocate a variable length array (VLA) on the stack without proper validation. Since the total size is not bounded, a malicious guest could use this flaw to influence the array length and cause the QEMU process to perform an excessive allocation on the stack, resulting in a denial of service.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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
Severity55% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
29.6%
KEV
Not listed

Published

May 26, 2021

Last Modified

November 21, 2024

References (16)

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuqemu-system-x86-xen (1:5.2+dfsg-9ubuntu3.1) @ hirsute2026-05-26ubuntu

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.

All Vendor Advisories

(2)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 12× in last 7d / 51× 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 108 total refreshes for this CVE.

  1. 2026-07-23 14:16 UTCEPSS rescore
  2. 2026-07-23 02:02 UTCEG score recompute
  3. 2026-07-22 22:49 UTCEG score recompute
  4. 2026-07-22 14:06 UTCEPSS rescore
  5. 2026-07-21 15:22 UTCEPSS rescore
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  7. 2026-07-20 17:05 UTCEPSS rescore
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  10. 2026-07-18 19:29 UTCOSV refresh
  11. 2026-07-18 10:02 UTCEPSS rescore
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  13. 2026-07-16 17:00 UTCEPSS rescore
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  25. 2026-07-09 19:07 UTCEPSS rescore
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  1. 2026-07-08 15:12 UTCEPSS rescore
  2. 2026-07-07 13:43 UTCEPSS rescore
  3. 2026-07-06 16:25 UTCEPSS rescore
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  5. 2026-07-06 02:21 UTCEPSS rescore
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  9. 2026-07-04 06:29 UTCEPSS rescore
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  11. 2026-07-02 16:57 UTCEPSS rescore
  12. 2026-07-01 15:04 UTCEPSS rescore
  13. 2026-07-01 02:18 UTCOSV refresh
  14. 2026-06-30 23:20 UTCEPSS rescore
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  16. 2026-06-28 14:05 UTCEPSS rescore
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  21. 2026-06-25 13:48 UTCEPSS rescore
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  23. 2026-06-24 14:03 UTCEPSS rescore
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  25. 2026-06-23 21:31 UTCEPSS rescore
  26. 2026-06-23 21:31 UTCEPSS rescore
  27. 2026-06-22 14:24 UTCEPSS rescore
  28. 2026-06-21 14:55 UTCEPSS rescore
  29. 2026-06-21 01:58 UTCEPSS rescore
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  31. 2026-06-19 19:24 UTCEPSS rescore
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  33. 2026-06-18 17:51 UTCEPSS rescore
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  35. 2026-06-17 17:51 UTCEPSS rescore
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  40. 2026-06-15 17:46 UTCEPSS rescore
  41. 2026-06-14 23:15 UTCEPSS rescore
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  43. 2026-06-13 22:58 UTCEPSS rescore
  44. 2026-06-13 22:58 UTCEPSS rescore
  45. 2026-06-13 04:43 UTCOSV refresh
  46. 2026-06-12 23:10 UTCEPSS rescore
  47. 2026-06-11 13:58 UTCEPSS rescore
  48. 2026-06-11 13:58 UTCEPSS rescore
  49. 2026-06-10 22:16 UTCEPSS rescore
  50. 2026-06-10 22:16 UTCEPSS rescore
  51. 2026-06-10 13:20 UTCEPSS rescore
  52. 2026-06-08 14:15 UTCEPSS rescore
  53. 2026-06-08 14:15 UTCEPSS rescore
  54. 2026-06-07 15:23 UTCEPSS rescore
  55. 2026-06-07 15:23 UTCEPSS rescore
  56. 2026-06-06 13:46 UTCEPSS rescore
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  58. 2026-06-05 22:45 UTCEPSS rescore
  59. 2026-06-05 06:09 UTCEPSS rescore
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  61. 2026-06-04 13:10 UTCEPSS rescore
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  63. 2026-06-02 20:11 UTCEPSS rescore
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  65. 2026-06-01 13:50 UTCEPSS rescore
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  67. 2026-05-31 22:29 UTCEPSS rescore
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  71. 2026-05-29 13:42 UTCEPSS rescore
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  73. 2026-05-28 13:43 UTCEPSS rescore
  74. 2026-05-27 13:39 UTCEPSS rescore
  75. 2026-05-27 13:39 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2021-3527?
CVE-2021-3527 is a medium vulnerability published on May 26, 2021. A flaw was found in the USB redirector device (usb-redir) of QEMU. Small USB packets are combined into a single, large transfer request, to reduce the overhead and improve performance. The combined size of the bulk transfer is used to dynamically allocate a variable length array (VLA) on the stack…
When was CVE-2021-3527 disclosed?
CVE-2021-3527 was first published in the National Vulnerability Database on May 26, 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-2021-3527 actively exploited?
CVE-2021-3527 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 29.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-3527?
CVE-2021-3527 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2021-3527?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-3527, 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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