CVE-2021-47383: tty: Fix out-of-bound vmalloc access in imageblit
Vulnerability summary
CVE-2021-47383 is a high (CVSS 7.8) Out-of-bounds Read vulnerability in linux. EPSS estimates a 0.27% chance of exploitation in the next 30 days, higher than 18.4% 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 76 · Related 71Timeline
- 21-05-2024PublishedVulnerability first disclosed.
- 05-08-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: tty: Fix out-of-bound vmalloc access in imageblit This issue happens when a userspace program does an ioctl FBIOPUT_VSCREENINFO passing the fb_var_screeninfo struct containing only the fields xres, yres, and bits_per_pixel with values. If this struct is the same as the previous ioctl, the vc_resize() detects it and doesn't call the resize_screen(), leaving the fb_var_screeninfo incomplete. And this leads to the updatescrollmode() calculates a wrong value to fbcon_display->vrows, which makes the real_y() return a wrong value of y, and that value, eventually, causes the imageblit to access an out-of-bound address value. To solve this issue I made the resize_screen() be called even if the screen does not need any resizing, so it will "fix and fill" the fb_var_screeninfo independently.
CVSS metrics
5 scores · 4 sources · 2 versions- 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 · calculated7.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:HDiffers
- NVDNIST7.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:HDiffers
EPSS trend
Probability
0.27%
Chance of exploitation in the next 30 days
Percentile
18%
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.
Ubuntu88 products
- linuxAll versions (No fix recorded) | < 4.15.0-163.171 | < 5.4.0-91.102
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 4.15.0-1116.123 | < 5.4.0-1060.63
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 7e71fcedfda6f7de18f850a6b36e78d78b04476f | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 70aed03b1d5a5df974f456cdc8eedb213c94bb8b | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 067c694d06040db6f0c65281bb358452ca6d85b9 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 8a6a240f52e14356386030d8958ae8b1761d2325 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 883f7897a25e3ce14a7f274ca4c73f49ac84002a | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < d570c48dd37dbe8fc6875d4461d01a9554ae2560 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 699d926585daa6ec44be556cdc1ab89e5d54557b | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 3b0c406124719b625b1aba431659f5cdc24a982c | 2.6.12
- linux_kernel< 4.4.286 | ≥ 4.5, < 4.9.285 | ≥ 4.10, < 4.14.249 | ≥ 4.15, < 4.19.209 | ≥ 4.20, < 5.4.151 | ≥ 5.5, < 5.10.71 | ≥ 5.11, < 5.14.10
Debian1 product
- linux< 5.14.12-1
3 vendors · 91 products
