CVE-2021-47191

HIGHNVD 7.17.1—
EchelonGraph scoreMEDIUM confidence

Score 7.1 from GitHub Security Advisory (severity: HIGH) published 2024-04-10. NVD baseline CVSS 7.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
7.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.1Exploit: None knownExposed: 0

A fix is available — apply it.

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

scsi: scsi_debug: Fix out-of-bound read in resp_readcap16()

The following warning was observed running syzkaller:

[ 3813.830724] sg_write: data in/out 65466/242 bytes for SCSI command 0x9e-- guessing data in; [ 3813.830724] program syz-executor not setting count and/or reply_len properly [ 3813.836956] ================================================================== [ 3813.839465] BUG: KASAN: stack-out-of-bounds in sg_copy_buffer+0x157/0x1e0 [ 3813.841773] Read of size 4096 at addr ffff8883cf80f540 by task syz-executor/1549 [ 3813.846612] Call Trace: [ 3813.846995] dump_stack+0x108/0x15f [ 3813.847524] print_address_description+0xa5/0x372 [ 3813.848243] kasan_report.cold+0x236/0x2a8 [ 3813.849439] check_memory_region+0x240/0x270 [ 3813.850094] memcpy+0x30/0x80 [ 3813.850553] sg_copy_buffer+0x157/0x1e0 [ 3813.853032] sg_copy_from_buffer+0x13/0x20 [ 3813.853660] fill_from_dev_buffer+0x135/0x370 [ 3813.854329] resp_readcap16+0x1ac/0x280 [ 3813.856917] schedule_resp+0x41f/0x1630 [ 3813.858203] scsi_debug_queuecommand+0xb32/0x17e0 [ 3813.862699] scsi_dispatch_cmd+0x330/0x950 [ 3813.863329] scsi_request_fn+0xd8e/0x1710 [ 3813.863946] __blk_run_queue+0x10b/0x230 [ 3813.864544] blk_execute_rq_nowait+0x1d8/0x400 [ 3813.865220] sg_common_write.isra.0+0xe61/0x2420 [ 3813.871637] sg_write+0x6c8/0xef0 [ 3813.878853] __vfs_write+0xe4/0x800 [ 3813.883487] vfs_write+0x17b/0x530 [ 3813.884008] ksys_write+0x103/0x270 [ 3813.886268] __x64_sys_write+0x77/0xc0 [ 3813.886841] do_syscall_64+0x106/0x360 [ 3813.887415] entry_SYSCALL_64_after_hwframe+0x44/0xa9

This issue can be reproduced with the following syzkaller log:

r0 = openat(0xffffffffffffff9c, &(0x7f0000000040)='./file0\x00', 0x26e1, 0x0) r1 = syz_open_procfs(0xffffffffffffffff, &(0x7f0000000000)='fd/3\x00') open_by_handle_at(r1, &(0x7f00000003c0)=ANY=[@ANYRESHEX], 0x602000) r2 = syz_open_dev$sg(&(0x7f0000000000), 0x0, 0x40782) write$binfmt_aout(r2, &(0x7f0000000340)=ANY=[@ANYBLOB="00000000deff000000000000000000000000000000000000000000000000000047f007af9e107a41ec395f1bded7be24277a1501ff6196a83366f4e6362bc0ff2b247f68a972989b094b2da4fb3607fcf611a22dd04310d28c75039d"], 0x126)

In resp_readcap16() we get "int alloc_len" value -1104926854, and then pass the huge arr_len to fill_from_dev_buffer(), but arr is only 32 bytes. This leads to OOB in sg_copy_buffer().

To solve this issue, define alloc_len as u32.

CVSS v3
7.1
EG Score
7.1(medium)
EG Risk
32(Track)
EG Risk 32/100SSVC: 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
Severity71% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
15%
KEV
Not listed

Published

April 10, 2024

Last Modified

August 5, 2026

Advisory Details (3)

Auto-updated Aug 5, 2026
No patch confirmed yet.
generic

scsi: scsi_debug: Fix out-of-bound read in resp_readcap16() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/4e3ace0051e7e504b55d239daab8789dd89b863c
generic

scsi: scsi_debug: Fix out-of-bound read in resp_readcap16() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/5b8bed6464ad6653586e30df046185fd816ad999
generic

scsi: scsi_debug: Fix out-of-bound read in resp_readcap16() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/3e20cb072679bdb47747ccc8bee3233a4cf0765a

Patch Availability(25)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-hwe-16.04-edge (4.15.0.237.249~16.04.1) @ xenial2026-05-24ubuntu
ubuntulinux-virtual-lts-xenial (4.4.0.268.274) @ xenial2026-05-24ubuntu
ubuntulinux-tools-gcp-fips (4.15.0.2081.79) @ bionic2026-05-24ubuntu
ubuntulinux-virtual-lts-xenial (4.4.0.268.302~14.04.1) @ trusty2026-05-24ubuntu
ubuntulinux-tools-fips (4.4.0.1113.114) @ xenial2026-05-24ubuntu
ubuntulinux-tools-azure-edge (4.15.0.1188.203~16.04.1) @ xenial2026-05-24ubuntu
ubuntulinux-tools-azure-fips (4.15.0.2097.93) @ bionic2026-05-24ubuntu
ubuntulinux-tools-azure (4.15.0.1188.203~14.04.1) @ trusty2026-05-24ubuntu
ubuntulinux-tools-aws (4.4.0.1143.140) @ trusty2026-05-24ubuntu
ubuntulinux-tools-raspi-hwe-18.04-edge (5.4.0.1129.142~18.04.1) @ bionic2026-05-24ubuntu
ubuntulinux-tools-ibm-lts-20.04 (5.4.0.1092.121) @ focal2026-05-24ubuntu
ubuntulinux-tools-bluefield (5.4.0.1105.101) @ focal2026-05-24ubuntu
ubuntulinux-tools-oracle-edge (5.4.0.1144.154~18.04.1) @ bionic2026-05-24ubuntu
ubuntulinux-xilinx-zynqmp-tools-5.4.0-1064 (5.4.0-1064.68) @ focal2026-05-24ubuntu
ubuntulinux-tools-aws-edge (5.4.0.1146.156~18.04.1) @ bionic2026-05-24ubuntu
ubuntulinux-tools-ibm-edge (5.4.0.1092.97~18.04.1) @ bionic2026-05-24ubuntu
ubuntulinux-tools-gcp-fips (5.4.0.1149.91) @ focal2026-05-24ubuntu
ubuntulinux-tools-fips (5.4.0.1120.117) @ focal2026-05-24ubuntu
ubuntulinux-tools-kvm (5.4.0.1133.129) @ focal2026-05-24ubuntu
ubuntulinux-tools-gcp-edge (5.4.0.1149.158~18.04.1) @ bionic2026-05-24ubuntu
ubuntulinux-tools-azure-fips (5.4.0.1151.88) @ focal2026-05-24ubuntu
ubuntulinux-virtual-hwe-18.04-edge (5.4.0.216.236~18.04.1) @ bionic2026-05-24ubuntu
ubuntulinux-tools-iot (5.4.0.1051.49) @ focal2026-05-24ubuntu
ubuntulinux-tools-raspi2-hwe-18.04-edge (5.4.0.1129.160) @ focal2026-05-24ubuntu
ubuntulinux-tools-aws-lts-20.04 (5.4.0.1146.143) @ focal2026-05-24ubuntu

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

(25)

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 14× in last 7d / 47× 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 120 total refreshes for this CVE.

  1. 2026-08-07 16:24 UTCEPSS rescore
  2. 2026-08-06 13:44 UTCEPSS rescore
  3. 2026-08-05 19:15 UTCEPSS rescore
  4. 2026-08-05 09:42 UTCEG score recompute
  5. 2026-08-05 09:42 UTCGHSA enrichment
  6. 2026-08-04 15:06 UTCEPSS rescore
  7. 2026-08-04 12:19 UTCEG score recompute
  8. 2026-08-04 12:19 UTCVendor advisory
  9. 2026-08-04 12:19 UTCGHSA enrichment
  10. 2026-08-04 10:34 UTCEPSS rescore
  11. 2026-08-04 09:53 UTCEG score recompute
  12. 2026-08-04 09:53 UTCVendor advisory
  13. 2026-08-04 09:53 UTCGHSA enrichment
  14. 2026-08-02 02:24 UTCEPSS rescore
  15. 2026-08-01 07:36 UTCOSV refresh
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  25. 2026-07-23 02:06 UTCEG score recompute
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  1. 2026-07-22 22:52 UTCEG score recompute
  2. 2026-07-22 14:06 UTCEPSS rescore
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  15. 2026-07-14 14:40 UTCOSV refresh
  16. 2026-07-13 22:27 UTCEPSS rescore
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  19. 2026-07-12 05:44 UTCEPSS rescore
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  25. 2026-07-07 13:43 UTCEPSS rescore
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  43. 2026-06-26 15:09 UTCOSV refresh
  44. 2026-06-25 13:48 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2021-47191?
CVE-2021-47191 is a high vulnerability published on April 10, 2024. In the Linux kernel, the following vulnerability has been resolved: scsi: scsidebug: Fix out-of-bound read in respreadcap16() The following warning was observed running syzkaller: [ 3813.830724] sg_write: data in/out 65466/242 bytes for SCSI command 0x9e-- guessing data in; [ 3813.830724] program…
When was CVE-2021-47191 disclosed?
CVE-2021-47191 was first published in the National Vulnerability Database on April 10, 2024, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-47191 actively exploited?
CVE-2021-47191 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 85.4% of all scored CVEs.
What is the CVSS score of CVE-2021-47191?
CVE-2021-47191 has a CVSS v3 base score of 7.1 (NVD).
How do I remediate CVE-2021-47191?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-47191, 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

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