CVE-2021-26931

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: 1%CVSS: 5.5Exploit: NoneExposed: 0

A fix is available — apply it.

An issue was discovered in the Linux kernel 2.6.39 through 5.10.16, as used in Xen. Block, net, and SCSI backends consider certain errors a plain bug, deliberately causing a kernel crash. For errors potentially being at least under the influence of guests (such as out of memory conditions), it isn't correct to assume a plain bug. Memory allocations potentially causing such crashes occur only when Linux is running in PV mode, though. This affects drivers/block/xen-blkback/blkback.c and drivers/xen/xen-scsiback.c.

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%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
42.3%
KEV
Not listed

Published

February 17, 2021

Last Modified

November 21, 2024

References (18)

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-image-virtual-lts-xenial (4.4.0.208.214) @ xenial2026-05-26ubuntu
ubuntulinux-image-virtual-hwe-18.04-edge (5.4.0.71.74) @ focal2026-05-26ubuntu
ubuntulinux-image-virtual-hwe-16.04-edge (4.15.0.143.130) @ bionic2026-05-26ubuntu
ubuntulinux-image-virtual-hwe-20.04-edge (5.8.0.53.58) @ groovy2026-05-26ubuntu

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

(5)

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 15× in last 7d / 52× 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 104 total refreshes for this CVE.

  1. 2026-07-23 14:16 UTCEPSS rescore
  2. 2026-07-23 01:59 UTCEG score recompute
  3. 2026-07-22 22:45 UTCEG score recompute
  4. 2026-07-22 14:06 UTCEPSS rescore
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  12. 2026-07-19 01:29 UTCOSV refresh
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  1. 2026-07-09 19:07 UTCEPSS rescore
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  11. 2026-07-02 16:57 UTCEPSS rescore
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  13. 2026-07-01 08:48 UTCOSV refresh
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  41. 2026-06-14 23:15 UTCEPSS rescore
  42. 2026-06-13 22:58 UTCEPSS rescore
  43. 2026-06-13 22:58 UTCEPSS rescore
  44. 2026-06-13 13:43 UTCOSV refresh
  45. 2026-06-12 23:10 UTCEPSS rescore
  46. 2026-06-11 13:58 UTCEPSS rescore
  47. 2026-06-10 22:16 UTCEPSS rescore
  48. 2026-06-10 13:20 UTCEPSS rescore
  49. 2026-06-08 14:15 UTCEPSS rescore
  50. 2026-06-07 15:23 UTCEPSS rescore
  51. 2026-06-07 15:23 UTCEPSS rescore
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  72. 2026-05-27 13:39 UTCEPSS rescore
  73. 2026-05-27 13:39 UTCEPSS rescore
  74. 2026-05-26 20:45 UTCEG score recompute
  75. 2026-05-26 20:45 UTCVendor advisory

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2021-26931?
CVE-2021-26931 is a medium vulnerability published on February 17, 2021. An issue was discovered in the Linux kernel 2.6.39 through 5.10.16, as used in Xen. Block, net, and SCSI backends consider certain errors a plain bug, deliberately causing a kernel crash. For errors potentially being at least under the influence of guests (such as out of memory conditions), it…
When was CVE-2021-26931 disclosed?
CVE-2021-26931 was first published in the National Vulnerability Database on February 17, 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-2021-26931 actively exploited?
CVE-2021-26931 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 42.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-26931?
CVE-2021-26931 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2021-26931?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-26931, 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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