CVE-2021-47649: udmabuf: validate ubuf->pagecount
Vulnerability summary
CVE-2021-47649 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.25% chance of exploitation in the next 30 days, higher than 16.1% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 6 · Related 4Timeline
- 26-02-2025PublishedVulnerability first disclosed.
- 11-05-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: udmabuf: validate ubuf->pagecount Syzbot has reported GPF in sg_alloc_append_table_from_pages(). The problem was in ubuf->pages == ZERO_PTR. ubuf->pagecount is calculated from arguments passed from user-space. If user creates udmabuf with list.size == 0 then ubuf->pagecount will be also equal to zero; it causes kmalloc_array() to return ZERO_PTR. Fix it by validating ubuf->pagecount before passing it to kmalloc_array().
CVSS metrics
3 scores · 3 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.25%
Chance of exploitation in the next 30 days
Percentile
16%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.25% 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 causeNo weakness data has been published for this record.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu102 products
- linux< 5.4.0-117.132 | < 5.15.0-37.39
- linux-allwinner-5.19All versions (No fix recorded)
- linux-aws< 5.4.0-1078.84 | < 5.15.0-1011.14
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ fbb0de795078190a9834b3409e4b009cfb18a6d4, < 5d50f851dd307c07ca5591297093f19967c834a9 | ≥ fbb0de795078190a9834b3409e4b009cfb18a6d4, < b267a8118c2b171bf7d67b90ed64154eeab9fae0 | ≥ fbb0de795078190a9834b3409e4b009cfb18a6d4, < 811b667cefbea9cb7511a874b169d6a92907137e | ≥ fbb0de795078190a9834b3409e4b009cfb18a6d4, < a3728d32fc61eb0fe283cb8ff60b2c8f751e2202 | ≥ fbb0de795078190a9834b3409e4b009cfb18a6d4, < 9e9b4a269f84d3230f2af84ff42322db676440d9 | ≥ fbb0de795078190a9834b3409e4b009cfb18a6d4, < 2b6dd600dd72573c23ea180b5b0b2f1813405882 | 4.20
- linux_kernel≥ 4.20, < 5.4.189 | ≥ 5.5, < 5.10.110 | ≥ 5.11, < 5.15.33 | ≥ 5.16, < 5.16.19 | ≥ 5.17, < 5.17.2
Debian1 product
- linux< 5.17.3-1
3 vendors · 105 products
