What is CVE-2021-33641?

CVE-2021-33641 is a high-severity vulnerability in Openeuler Byacc, classified under Use After Free. CVSS score: 7.8/10. Published 2023-01-20.

How severe is CVE-2021-33641?

High severity. CVSS v3 base score is 7.8 out of 10.

Use After Free in Openeuler Byacc

CVE-2021-33641

When processing files, malloc stores the data of the current line. When processing comments, malloc incorrectly accesses the released memory (use after free).

Vulnerability class: Use-After-Free

Published 2023-01-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.003 (17.2th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 17th percentile — 17.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Openeuler Byacc
Byacc — versions <1.9.20200330 and <2.0.20210808

Weakness classification (CWE)

CWE-416 — Use After Free

References

gitee.com/src-openeuler/byacc/commit/50225f48c6b53e9d7c936681a06682404cb8ec4d (Permissions Required, Third Party Advisory)

Frequently asked questions

What is CVE-2021-33641?: CVE-2021-33641 is a high-severity vulnerability in Openeuler Byacc, classified under Use After Free. CVSS score: 7.8/10. Published 2023-01-20.
How severe is CVE-2021-33641?: High severity. CVSS v3 base score is 7.8 out of 10.