CVE-2021-47343: dm btree remove: assign new_root only when removal succeeds
Vulnerability summary
CVE-2021-47343 is a high (CVSS 7.8) vulnerability in linux. EPSS estimates a 0.27% chance of exploitation in the next 30 days, higher than 19.2% of scored vulnerabilities.
Not severe (CVSS 7.8, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 5 · Related 5Timeline
- 21-05-2024PublishedVulnerability first disclosed.
- 05-08-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: dm btree remove: assign new_root only when removal succeeds remove_raw() in dm_btree_remove() may fail due to IO read error (e.g. read the content of origin block fails during shadowing), and the value of shadow_spine::root is uninitialized, but the uninitialized value is still assign to new_root in the end of dm_btree_remove(). For dm-thin, the value of pmd->details_root or pmd->root will become an uninitialized value, so if trying to read details_info tree again out-of-bound memory may occur as showed below: general protection fault, probably for non-canonical address 0x3fdcb14c8d7520 CPU: 4 PID: 515 Comm: dmsetup Not tainted 5.13.0-rc6 Hardware name: QEMU Standard PC RIP: 0010:metadata_ll_load_ie+0x14/0x30 Call Trace: sm_metadata_count_is_more_than_one+0xb9/0xe0 dm_tm_shadow_block+0x52/0x1c0 shadow_step+0x59/0xf0 remove_raw+0xb2/0x170 dm_btree_remove+0xf4/0x1c0 dm_pool_delete_thin_device+0xc3/0x140 pool_message+0x218/0x2b0 target_message+0x251/0x290 ctl_ioctl+0x1c4/0x4d0 dm_ctl_ioctl+0xe/0x20 __x64_sys_ioctl+0x7b/0xb0 do_syscall_64+0x40/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae Fixing it by only assign new_root when removal succeeds
CVSS metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HDiffers
- NVDNIST5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HDiffers
EPSS trend
Probability
0.27%
Chance of exploitation in the next 30 days
Percentile
19%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.27% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu87 products
- linuxAll versions (No fix recorded) | < 4.15.0-156.163 | < 5.4.0-84.94
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 4.15.0-1111.118 | < 5.4.0-1056.59
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4, < 4c84b3e0728ffe10d89c633694c35a02b5c477dc | ≥ 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4, < c154775619186781aaf8a99333ac07437a1768d5 | ≥ 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4, < 73f27adaa73e3057a9ec464e33c4f54d34ea5de3 | ≥ 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4, < 8fbae4a1bdb5b889490cdee929e68540151536e5 | ≥ 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4, < 964d57d1962d7e68f0f578f05d9ae4a104d74851 | ≥ 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4, < ba47e65a5de3e0e8270301a409fc63d3129fdb9e | ≥ 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4, < 89bf942314b78d454db92427201421b5dec132d9 | ≥ 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4, < ad365e9351ac2b450e7e79932ff6abf59342d91a | ≥ 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4, < b6e58b5466b2959f83034bead2e2e1395cca8aeb | 3.2
- linux_kernel< 4.4.276 | ≥ 4.5, < 4.9.276 | ≥ 4.10, < 4.14.240 | ≥ 4.15, < 4.19.198 | ≥ 4.20, < 5.4.133 | ≥ 5.5, < 5.10.51 | ≥ 5.11, < 5.12.18 | ≥ 5.13, < 5.13.3
Debian1 product
- linux< 5.14.6-1
3 vendors · 90 products
