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CVE-2021-33642

20
FAUCET Score

CVE-2021-33642 describes an infinite loop vulnerability in the next_inline() function of more_curly() within openeuler byacc. This medium-severity flaw (CVSS 5.5) can lead to a denial of service (availability impact) when a specially crafted file is processed, requiring user interaction to trigger. There is currently no evidence of active exploitation, public 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

5.5MEDIUM

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.22%
Probability of exploitation in next 30 days
EPSS Percentile
12.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0022 is in the 16th percentile among its peer group of 5,760 CVEs.

Social Chatter

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

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: byacc

Vendor Advisories (1)

redhatCVE-2021-33642Low

byacc: an infinite loop occurs in next_inline() of the more_curly() function

May 28, 2022

References

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