7.8

CVE-2021-33641: openeuler byacc Use After Free

Modified
Published 20-01-2023Last modified 03-04-2025

Vulnerability summary

CVE-2021-33641 is a high (CVSS 7.8) Use After Free vulnerability in openeuler byacc. EPSS estimates a 0.28% chance of exploitation in the next 30 days, higher than 20.2% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 7.8, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
7.8/10
010
High · v3.1 (CVE.org)
EPSS score
0.28%
0%100%
Low · +0.01 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 20-01-2023
    PublishedVulnerability first disclosed.
  2. 03-04-2025
    Last modifiedVulnerability information updated.

Description

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

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.28%

Chance of exploitation in the next 30 days

Percentile

20%

Versus all other CVEs

30-day change

Increase +0.01 pp

From 0.27% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: local access, no authentication, user interaction (CVSS vector). Other conditions: not stated in public data.

Openeuler1 product
  • byacc< 1.9.20200330 | ≥ 2.0, < 2.0.20210808

1 vendor · 1 product

References

1 links