CVE-2021-3491

Exploitation

Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.

SSVC decision

Not assessed by CISA

EPSS probability

0.64% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 48.3% of scored records. A rank, not a probability.

NVD base score

8.8 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

NVD analysis status

Modified. NVD last modified this record on 2026-06-17.

Red Hat severity

Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2021-06-04 01:40Z5 YR AGO

Last updated

2024-09-16 22:09Z1 YR AGO

Reserved

2021-04-09

Assigning CNA

canonical

Record state

PUBLISHED

Severity

High (CVSS 7.8)

CNA CVSS vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

Weaknesses

• CWE-131Incorrect Calculation of Buffer SizeBase
• CWE-787Out-of-bounds WriteBase
• CWE-119Improper Restriction of Operations within the Bounds of a Memory BufferClass

Data version

5.1

Document digest

4543ec0071ae4968c4c68926181929acace81c70d16215443a98c48a1113dc81

• ubuntu.comhttps://ubuntu.com/security/notices/USN-4950-1vendor-advisoryx_refsource_UBUNTU
• ubuntu.comhttps://ubuntu.com/security/notices/USN-4949-1vendor-advisoryx_refsource_UBUNTU
• www.openwall.com[oss-security] CVE-2021-3491 - Linux kernel io_uring PROVIDE_BUFFERS MAX_RW_COUNT bypasshttps://www.openwall.com/lists/oss-security/2021/05/11/13mailing-listx_refsource_MLIST
• git.kernel.orghttps://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d1f82808877bb10d3deee7cf3374a4eb3fb582dbx_refsource_MISC
• www.zerodayinitiative.comhttps://www.zerodayinitiative.com/advisories/ZDI-21-589/x_refsource_MISC
• security.netapp.comhttps://security.netapp.com/advisory/ntap-20210716-0004/x_refsource_CONFIRM