CVE-2021-47641: video: fbdev: cirrusfb: check pixclock to avoid divide by zero
Vulnerability summary
CVE-2021-47641 is a medium (CVSS 5.5) Divide By Zero vulnerability in linux. EPSS estimates a 0.25% chance of exploitation in the next 30 days, higher than 16.8% 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 6Timeline
- 26-02-2025PublishedVulnerability first disclosed.
- 11-05-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: video: fbdev: cirrusfb: check pixclock to avoid divide by zero Do a sanity check on pixclock value to avoid divide by zero. If the pixclock value is zero, the cirrusfb driver will round up pixclock to get the derived frequency as close to maxclock as possible. Syzkaller reported a divide error in cirrusfb_check_pixclock. divide error: 0000 [#1] SMP KASAN PTI CPU: 0 PID: 14938 Comm: cirrusfb_test Not tainted 5.15.0-rc6 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2 RIP: 0010:cirrusfb_check_var+0x6f1/0x1260 Call Trace: fb_set_var+0x398/0xf90 do_fb_ioctl+0x4b8/0x6f0 fb_ioctl+0xeb/0x130 __x64_sys_ioctl+0x19d/0x220 do_syscall_64+0x3a/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae
CVSS metrics
5 scores · 4 sources · 2 versions- 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
- NVDNIST5.5MediumCVSS: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
17%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.26% 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.
Ubuntu107 products
- linuxAll versions (No fix recorded) | < 4.15.0-189.200 | < 5.4.0-117.132 | < 5.15.0-37.39
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 4.15.0-1137.148 | < 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≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < c656d04247a2654ede5cead2ecbf83431dad5261 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 1d3fb46439ad4e8f0c5739eb33d1875ac9e0f135 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 40b13e3d85744210db13457785646634e2d056bd | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 53a2088a396cfa1da92690a1da289634cd73bf0d | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 8c7e2141fb89c620ab4e41512e262fbf25b8260d | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 6fe23ff94e7840097202e85c148688940b37c9b1 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 45800c42ef000f417270bcfc08630e42486fca99 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < e498b504f8c81b07efab9febf8503448de4dc9cf | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 5c6f402bdcf9e7239c6bc7087eda71ac99b31379 | 2.6.12
- linux_kernel< 4.9.311 | ≥ 4.10, < 4.14.276 | ≥ 4.15, < 4.19.238 | ≥ 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 · 110 products
