CVE-2021-33391 json
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.
published 2023-02-17 3 y ago modified 2026-06-17 4 mo ago also EUVD-2021-20097
- cvss
- 9.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.1%
- EPSS 1.1% chance of exploitation in 30 days, percentile 66%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- tidy-html5 Debian 14, Debian 13 2:5.8.0-2
debian advisories DEBIAN-CVE-2021-33391
- tidy-html5 Ubuntu 20.04 LTS 2:5.6.0-11ubuntu0.20.04.1
- tidy-html5 Ubuntu 22.04 LTS 2:5.6.0-11ubuntu0.22.04.1
- tidy-html5 Ubuntu 24.04 LTS 2:5.6.0-11ubuntu1
ubuntu advisories UBUNTU-CVE-2021-33391
Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0
- tidy CBL-Mariner 2.0, Azure Linux 3.0 5.8.0-6
azure linux advisories AZL-13687AZL-35324
Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- total
- Assessed
- 19 mo ago
Exploit prediction
1.13% chance of exploitation in the next 30 days, higher than 66% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/htacg/tidy-html5/issues/946 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CISA ADP | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVD | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CNA | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
Classification
- Weakness
-
- CWE-416 Use After Free
References
-
github.com
/htacg/tidy-html5/issues/946
exploit, patch
Sources
- CVE List CVE-2021-33391
- NVD CVE-2021-33391
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.