What is CVE-2021-33642?

CVE-2021-33642 is a medium-severity vulnerability in Openeuler Byacc, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 5.5/10. Published 2023-01-20.

How severe is CVE-2021-33642?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Vulnerability in Openeuler Byacc

CVE-2021-33642

When a file is processed, an infinite loop occurs in next_inline() of the more_curly() function.

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

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.002 (11.4th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 11th percentile — 11.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

Openeuler Byacc
Byacc — versions <1.9.20200330 and <2.0.20210808

Weakness classification (CWE)

CWE-835 — Loop with Unreachable Exit Condition (Infinite Loop)

References

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

Frequently asked questions

What is CVE-2021-33642?: CVE-2021-33642 is a medium-severity vulnerability in Openeuler Byacc, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 5.5/10. Published 2023-01-20.
How severe is CVE-2021-33642?: Medium severity. CVSS v3 base score is 5.5 out of 10.