5.5

CVE-2021-47217: x86/hyperv: Fix NULL deref in set_hv_tscchange_cb() if Hyper-V setup fails

Analyzed
AliasesUBUNTU-CVE-2021-47217DEBIAN-CVE-2021-47217
Published 10-04-2024Last modified 11-05-2026

Vulnerability summary

CVE-2021-47217 is a medium (CVSS 5.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.24% chance of exploitation in the next 30 days, higher than 14.5% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.5/10
010
Medium · v3.1 (NVD)
EPSS score
0.24%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 8 · Related 8
SUSE-SU-2024:1641-1SUSE-SU-2024:1643-1SUSE-SU-2024:1644-1SUSE-SU-2024:1646-1SUSE-SU-2024:1647-1SUSE-SU-2024:1659-1

Timeline

  1. 10-04-2024
    PublishedVulnerability first disclosed.
  2. 11-05-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: x86/hyperv: Fix NULL deref in set_hv_tscchange_cb() if Hyper-V setup fails Check for a valid hv_vp_index array prior to derefencing hv_vp_index when setting Hyper-V's TSC change callback. If Hyper-V setup failed in hyperv_init(), the kernel will still report that it's running under Hyper-V, but will have silently disabled nearly all functionality. BUG: kernel NULL pointer dereference, address: 0000000000000010 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] SMP CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.15.0-rc2+ #75 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:set_hv_tscchange_cb+0x15/0xa0 Code: <8b> 04 82 8b 15 12 17 85 01 48 c1 e0 20 48 0d ee 00 01 00 f6 c6 08 ... Call Trace: kvm_arch_init+0x17c/0x280 kvm_init+0x31/0x330 vmx_init+0xba/0x13a do_one_initcall+0x41/0x1c0 kernel_init_freeable+0x1f2/0x23b kernel_init+0x16/0x120 ret_from_fork+0x22/0x30

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.24%

Chance of exploitation in the next 30 days

Percentile

15%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.24% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu84 products
  • linux< 5.4.0-97.110
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 5.4.0-1064.67
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 93286261de1b46339aa27cd4c639b21778f6cade, < b20ec58f8a6f4fef32cc71480ddf824584e24743 | ≥ 93286261de1b46339aa27cd4c639b21778f6cade, < b0e44dfb4e4c699cca33ede431b8d127e6e8d661 | ≥ 93286261de1b46339aa27cd4c639b21778f6cade, < 9c177eee116cf888276d3748cb176e72562cfd5c | ≥ 93286261de1b46339aa27cd4c639b21778f6cade, < 8823ea27fff6084bbb4bc71d15378fae0220b1d8 | ≥ 93286261de1b46339aa27cd4c639b21778f6cade, < daf972118c517b91f74ff1731417feb4270625a4 | 4.16
  • linux_kernel≥ 4.16, < 4.19.218 | ≥ 4.20, < 5.4.162 | ≥ 5.5, < 5.10.82 | ≥ 5.11, < 5.15.5 | 5.16:rc1
Debian1 product
  • linux< 5.15.5-1

3 vendors · 87 products

References

9 links