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CVE-2021-33641

24
FAUCET Score

CVE-2021-33641 is a high-severity use-after-free vulnerability (CWE-416) affecting openeuler byacc, where incorrect memory access occurs during comment processing after memory has been freed. With a CVSS score of 7.8, this vulnerability can be exploited locally with low attack complexity, potentially leading to high impact on confidentiality, integrity, and availability. There is currently no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.9.20200330CPE matchmatch criteria
cpe:2.3:a:openeuler:byacc:*:*:*:*:*:*:*:*
>= 2.0, < 2.0.20210808CPE matchmatch criteria
cpe:2.3:a:openeuler:byacc:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.8HIGH

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.27%
Probability of exploitation in next 30 days
EPSS Percentile
19.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0027 is in the 18th percentile among its peer group of 11,616 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: byacc

Vendor Advisories (1)

redhatCVE-2021-33641Moderate

byacc: malloc incorrectly accessing released memory leads to use after free

May 28, 2022

References

gitee.com / src-openeuler/byacc/commit/50225f48c6b53e9d7c936681a06682404cb8ec4d
Permissions RequiredThird Party Advisory