CVE-2021-28703

HIGHNVD 7.07.0—
EchelonGraph scoreMEDIUM confidence

Score 7.0 from GitHub Security Advisory (severity: HIGH) published 2021-12-08. NVD baseline CVSS 7.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
7.0EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.0Exploit: None knownExposed: 0

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

grant table v2 status pages may remain accessible after de-allocation (take two) Guest get permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime. Grant table v2 status pages, however, get de-allocated when a guest switched (back) from v2 to v1. The freeing of such pages requires that the hypervisor know where in the guest these pages were mapped. The hypervisor tracks only one use within guest space, but racing requests from the guest to insert mappings of these pages may result in any of them to become mapped in multiple locations. Upon switching back from v2 to v1, the guest would then retain access to a page that was freed and perhaps re-used for other purposes. This bug was fortuitously fixed by code cleanup in Xen 4.14, and backported to security-supported Xen branches as a prerequisite of the fix for XSA-378.

CVSS v3
7.0
EG Score
7.0(medium)
EG Risk
36(Track)
EG Risk 36/100SSVC: 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
Severity70% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
23%
KEV
Not listed

Published

December 7, 2021

Last Modified

November 21, 2024

References (4)

Affected Packages

(18 across 18 ecosystems)
Alpine:v3.11(1)
PackageVulnerable rangeFixed inDependents
xen—4.13.4-r0—
Alpine:v3.12(1)
PackageVulnerable rangeFixed inDependents
xen—4.13.4-r0—
Alpine:v3.13(1)
PackageVulnerable rangeFixed inDependents
xen—4.14.5-r0—
Alpine:v3.14(1)
PackageVulnerable rangeFixed inDependents
xen—4.15.2-r0—
Alpine:v3.15(1)
PackageVulnerable rangeFixed inDependents
xen—4.15.2-r0—
Alpine:v3.16(1)
PackageVulnerable rangeFixed inDependents
xen—4.15.1-r1—
Alpine:v3.17(1)
PackageVulnerable rangeFixed inDependents
xen—4.15.1-r1—
Alpine:v3.18(1)
PackageVulnerable rangeFixed inDependents
xen—4.15.1-r1—
Alpine:v3.19(1)
PackageVulnerable rangeFixed inDependents
xen—4.15.1-r1—
Alpine:v3.20(1)
PackageVulnerable rangeFixed inDependents
xen—4.15.1-r1—
Alpine:v3.21(1)
PackageVulnerable rangeFixed inDependents
xen—4.15.1-r1—
Alpine:v3.22(1)
PackageVulnerable rangeFixed inDependents
xen—4.15.1-r1—
Alpine:v3.23(1)
PackageVulnerable rangeFixed inDependents
xen—4.15.1-r1—
Alpine:v3.24(1)
PackageVulnerable rangeFixed inDependents
xen—4.15.1-r1—
Debian:11(1)
PackageVulnerable rangeFixed inDependents
xen—4.14.0+80-gd101b417b7-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
xen—4.14.0+80-gd101b417b7-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
xen—4.14.0+80-gd101b417b7-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
xen—4.14.0+80-gd101b417b7-1—

Data Freshness Timeline

(refreshed 8× in last 7d / 31× 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 153 total refreshes for this CVE.

  1. 2026-09-07 15:58 UTCEPSS rescore
  2. 2026-09-06 13:44 UTCEPSS rescore
  3. 2026-09-06 02:30 UTCOSV refresh
  4. 2026-09-05 15:25 UTCEPSS rescore
  5. 2026-09-04 13:57 UTCEPSS rescore
  6. 2026-09-04 05:03 UTCEPSS rescore
  7. 2026-09-04 05:03 UTCEPSS rescore
  8. 2026-09-02 14:08 UTCEPSS rescore
  9. 2026-09-01 13:50 UTCEPSS rescore
  10. 2026-09-01 03:32 UTCEPSS rescore
  11. 2026-08-30 19:14 UTCEPSS rescore
  12. 2026-08-30 01:19 UTCEPSS rescore
  13. 2026-08-28 21:37 UTCEPSS rescore
  14. 2026-08-27 14:22 UTCEPSS rescore
  15. 2026-08-26 14:42 UTCEPSS rescore
  16. 2026-08-25 13:45 UTCEPSS rescore
  17. 2026-08-24 14:12 UTCEPSS rescore
  18. 2026-08-23 00:16 UTCEPSS rescore
  19. 2026-08-21 23:46 UTCEPSS rescore
  20. 2026-08-20 22:52 UTCEPSS rescore
  21. 2026-08-19 17:01 UTCEPSS rescore
  22. 2026-08-19 13:29 UTCOSV refresh
  23. 2026-08-18 13:45 UTCEPSS rescore
  24. 2026-08-17 13:44 UTCEPSS rescore
  25. 2026-08-16 14:53 UTCEPSS rescore
Show 75 more
  1. 2026-08-16 02:11 UTCEPSS rescore
  2. 2026-08-16 02:11 UTCEPSS rescore
  3. 2026-08-15 01:27 UTCEPSS rescore
  4. 2026-08-13 21:57 UTCEPSS rescore
  5. 2026-08-12 13:47 UTCEPSS rescore
  6. 2026-08-11 13:38 UTCEPSS rescore
  7. 2026-08-09 13:43 UTCEPSS rescore
  8. 2026-08-07 16:23 UTCEPSS rescore
  9. 2026-08-06 13:43 UTCEPSS rescore
  10. 2026-08-05 19:14 UTCEPSS rescore
  11. 2026-08-04 15:06 UTCEPSS rescore
  12. 2026-08-04 10:34 UTCEPSS rescore
  13. 2026-08-04 08:57 UTCOSV refresh
  14. 2026-08-03 10:33 UTCEPSS rescore
  15. 2026-08-02 02:24 UTCEPSS rescore
  16. 2026-08-01 04:13 UTCEPSS rescore
  17. 2026-07-30 16:25 UTCEPSS rescore
  18. 2026-07-30 16:25 UTCEPSS rescore
  19. 2026-07-30 01:28 UTCEPSS rescore
  20. 2026-07-30 01:27 UTCEPSS rescore
  21. 2026-07-28 15:33 UTCEPSS rescore
  22. 2026-07-26 14:52 UTCEPSS rescore
  23. 2026-07-26 14:52 UTCEPSS rescore
  24. 2026-07-25 14:15 UTCEPSS rescore
  25. 2026-07-24 14:15 UTCEPSS rescore
  26. 2026-07-23 14:16 UTCEPSS rescore
  27. 2026-07-23 01:59 UTCEG score recompute
  28. 2026-07-22 22:46 UTCEG score recompute
  29. 2026-07-22 14:06 UTCEPSS rescore
  30. 2026-07-22 14:06 UTCEPSS rescore
  31. 2026-07-21 15:22 UTCEPSS rescore
  32. 2026-07-21 15:22 UTCEPSS rescore
  33. 2026-07-20 17:05 UTCEPSS rescore
  34. 2026-07-19 14:28 UTCEPSS rescore
  35. 2026-07-19 02:27 UTCEPSS rescore
  36. 2026-07-19 02:27 UTCEPSS rescore
  37. 2026-07-18 10:02 UTCEPSS rescore
  38. 2026-07-18 10:02 UTCEPSS rescore
  39. 2026-07-18 06:29 UTCOSV refresh
  40. 2026-07-16 17:00 UTCEPSS rescore
  41. 2026-07-15 16:55 UTCEPSS rescore
  42. 2026-07-15 16:55 UTCEPSS rescore
  43. 2026-07-15 01:58 UTCEPSS rescore
  44. 2026-07-13 22:27 UTCEPSS rescore
  45. 2026-07-13 22:27 UTCEPSS rescore
  46. 2026-07-13 06:10 UTCEPSS rescore
  47. 2026-07-12 05:44 UTCEPSS rescore
  48. 2026-07-12 05:44 UTCEPSS rescore
  49. 2026-07-11 08:25 UTCEPSS rescore
  50. 2026-07-11 08:25 UTCEPSS rescore
  51. 2026-07-09 19:07 UTCEPSS rescore
  52. 2026-07-08 15:12 UTCEPSS rescore
  53. 2026-07-07 13:43 UTCEPSS rescore
  54. 2026-07-06 16:25 UTCEPSS rescore
  55. 2026-07-06 16:25 UTCEPSS rescore
  56. 2026-07-06 02:21 UTCEPSS rescore
  57. 2026-07-06 02:21 UTCEPSS rescore
  58. 2026-07-05 02:28 UTCEPSS rescore
  59. 2026-07-04 06:29 UTCEPSS rescore
  60. 2026-07-04 06:29 UTCEPSS rescore
  61. 2026-07-02 16:57 UTCEPSS rescore
  62. 2026-07-01 15:03 UTCEPSS rescore
  63. 2026-06-30 23:20 UTCEPSS rescore
  64. 2026-06-30 23:20 UTCEPSS rescore
  65. 2026-06-30 03:30 UTCOSV refresh
  66. 2026-06-29 14:04 UTCEPSS rescore
  67. 2026-06-28 14:05 UTCEPSS rescore
  68. 2026-06-28 04:54 UTCEPSS rescore
  69. 2026-06-28 04:54 UTCEPSS rescore
  70. 2026-06-27 03:06 UTCEPSS rescore
  71. 2026-06-27 03:06 UTCEPSS rescore
  72. 2026-06-25 13:48 UTCEPSS rescore
  73. 2026-06-25 13:48 UTCEPSS rescore
  74. 2026-06-24 14:03 UTCEPSS rescore
  75. 2026-06-24 14:03 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-28703?
CVE-2021-28703 is a high vulnerability published on December 7, 2021. grant table v2 status pages may remain accessible after de-allocation (take two) Guest get permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime. Grant table v2 status pages, however, get de-allocated…
When was CVE-2021-28703 disclosed?
CVE-2021-28703 was first published in the National Vulnerability Database on December 7, 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-2021-28703 actively exploited?
CVE-2021-28703 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 76.8% of all scored CVEs.
What is the CVSS score of CVE-2021-28703?
CVE-2021-28703 has a CVSS v3 base score of 7.0 (NVD).
How do I remediate CVE-2021-28703?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-28703, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-28703

Explore →

Is Your Infrastructure Affected by CVE-2021-28703?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs