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CVE-2021-33391

30
FAUCET Score

CVE-2021-33391 is a critical arbitrary code execution vulnerability affecting HTACG HTML Tidy v5.7.28, specifically within the CleanNode() function via the -g option. With a CVSS score of 9.8, this flaw presents a severe risk as it can be exploited remotely without user interaction, leading to complete compromise of confidentiality, integrity, and availability. Despite its high severity, there is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
5.7.28CPE matchmatch criteria
cpe:2.3:a:htacg:tidy:5.7.28:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.13%
Probability of exploitation in next 30 days
EPSS Percentile
63.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0113 is in the 49th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 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

Patch Available

Vendor Patches (7)

github_advisorypatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: azl3 tidy 5.8.0-6 on Azure Linux 3.0Fixed in: 5.8.0-6
microsoftpatch availablevia msrc
Product: 19087-17084Fixed in: 5.8.0-6
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 x64Fixed in: 5.8.0-6
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 ARMFixed in: 5.8.0-6
microsoftpatch availablevia msrc
Product: Azure Linux 3.0 x64Fixed in: 5.8.0-6
microsoftpatch availablevia msrc
Product: Azure Linux 3.0 ARMFixed in: 5.8.0-6

Vendor Advisories (2)

microsoft2024-Jun/CVE-2021-33391

CVE-2021-33391

Jun 11, 2024
microsoft2023-Feb/CVE-2021-33391Critical

An issue in HTACG HTML Tidy v5.7.28 allows attacker to execute arbitrary code via the -g option of the CleanNode() function in gdoc.c.

Feb 14, 2023

References

github.com / htacg/tidy-html5/issues/946
ExploitPatch