CVE-2021-47640

HIGHNVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2025-03-18. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 0

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

In the Linux kernel, the following vulnerability has been resolved:

powerpc/kasan: Fix early region not updated correctly

The shadow's page table is not updated when PTE_RPN_SHIFT is 24 and PAGE_SHIFT is 12. It not only causes false positives but also false negative as shown the following text.

Fix it by bringing the logic of kasan_early_shadow_page_entry here.

  • False Positive:
================================================================== BUG: KASAN: vmalloc-out-of-bounds in pcpu_alloc+0x508/0xa50 Write of size 16 at addr f57f3be0 by task swapper/0/1

CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-12267-gdebe436e77c7 #1 Call Trace: [c80d1c20] [c07fe7b8] dump_stack_lvl+0x4c/0x6c (unreliable) [c80d1c40] [c02ff668] print_address_description.constprop.0+0x88/0x300 [c80d1c70] [c02ff45c] kasan_report+0x1ec/0x200 [c80d1cb0] [c0300b20] kasan_check_range+0x160/0x2f0 [c80d1cc0] [c03018a4] memset+0x34/0x90 [c80d1ce0] [c0280108] pcpu_alloc+0x508/0xa50 [c80d1d40] [c02fd7bc] __kmem_cache_create+0xfc/0x570 [c80d1d70] [c0283d64] kmem_cache_create_usercopy+0x274/0x3e0 [c80d1db0] [c2036580] init_sd+0xc4/0x1d0 [c80d1de0] [c00044a0] do_one_initcall+0xc0/0x33c [c80d1eb0] [c2001624] kernel_init_freeable+0x2c8/0x384 [c80d1ef0] [c0004b14] kernel_init+0x24/0x170 [c80d1f10] [c001b26c] ret_from_kernel_thread+0x5c/0x64

Memory state around the buggy address: f57f3a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f57f3b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >f57f3b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ f57f3c00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f57f3c80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ==================================================================

  • False Negative (with KASAN tests):
================================================================== Before fix: ok 45 - kmalloc_double_kzfree # vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039 KASAN failure expected in "((volatile char *)area)[3100]", but none occurred not ok 46 - vmalloc_oob not ok 1 - kasan

================================================================== After fix: ok 1 - kasan

CVSS v3
7.8
EG Score
7.8(medium)
EG Risk
35(Track)
EG Risk 35/100SSVC: 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
Severity78% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
18%
KEV
Not listed

Published

February 26, 2025

Last Modified

October 1, 2025

References (6)

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 5.10.92-2 (11 versions)5.10.113-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux—5.17.3-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux—5.17.3-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux—5.17.3-1—

Weakness Classification(1)

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

Data Freshness Timeline

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-47640?
CVE-2021-47640 is a high vulnerability published on February 26, 2025. In the Linux kernel, the following vulnerability has been resolved: powerpc/kasan: Fix early region not updated correctly The shadow's page table is not updated when PTERPNSHIFT is 24 and PAGE_SHIFT is 12. It not only causes false positives but also false negative as shown the following text. Fix…
When was CVE-2021-47640 disclosed?
CVE-2021-47640 was first published in the National Vulnerability Database on February 26, 2025, with the most recent update on October 1, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-47640 actively exploited?
CVE-2021-47640 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 81.9% of all scored CVEs.
What is the CVSS score of CVE-2021-47640?
CVE-2021-47640 has a CVSS v3 base score of 7.8 (NVD).
How do I remediate CVE-2021-47640?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-47640, 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-2021-47640

Explore →

Is Your Infrastructure Affected by CVE-2021-47640?

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

Start Free Scan →Browse All CVEs