---
title: "CVE-2025-6497\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2025-6497?format=md
keywords: index, follow
---

# CVE-2025-6497

Publication date 23 June 2025

Last updated 17 August 2026

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**3.3 · Low**

[Score breakdown](https://ubuntu.com/security/CVE-2025-6497?format=md#impact-score)

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## Description

A vulnerability was found in HTACG tidy-html5 5.8.0. It has been rated as
problematic. This issue affects the function prvTidyParseNamespace of the
file src/parser.c. The manipulation leads to reachable assertion. Attacking
locally is a requirement. The exploit has been disclosed to the public and
may be used.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2025-6497?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| tidy-html5 | 26.04 LTS resolute | Vulnerable, fix deferred |
| 25.10 questing | Ignored end of life, was deferred [2026-08-17] |
| 25.04 plucky | Ignored end of life, was deferred [2026-08-17] |
| 24.10 oracular | Ignored end of life, was deferred [2026-08-17] |
| 24.04 LTS noble | Vulnerable, fix deferred |
| 22.04 LTS jammy | Vulnerable, fix deferred |
| 20.04 LTS focal | Vulnerable, fix deferred |
| 18.04 LTS bionic | Vulnerable, fix deferred |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

## Notes

---

### [mdeslaur](https://launchpad.net/~mdeslaur)

as of 2026-08-17, there is no upstream fix for this issue

## Severity score breakdown

CVSS version:

CVSS v4.0

[CVSS v4.0](https://ubuntu.com/security/CVE-2025-6497?format=md)
[CVSS v3.0](https://ubuntu.com/security/CVE-2025-6497?format=md)

**Base score**

1.9 · Low

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Local |
  | Attack complexity | Low |
  | Attack requirements | None |
  | Privileges required | Low |
  | User interaction | None |
  | Vulnerable system - Confidentiality impact | None |
  | Vulnerable system - Integrity impact | None |
  | Vulnerable system - Availability impact | Low |
  | Subsequent system - Confidentiality impact | None |
  | Subsequent system - Integrity impact | None |
  | Subsequent system - Availability impact | None |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 1.9 · Low |
  | Base + Threat score | - |
  | Base + Environmental score | - |
  | Base + Threat + Environmental score | - |

**Vector:** CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2025-6497)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2025-6497)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2025-6497)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2025-6497)

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2025-6497>
* <https://github.com/user-attachments/files/19825297/tidy-html5_crash_2.txt>
* <https://vuldb.com/?ctiid.313613>
* <https://vuldb.com/?id.313613>
* <https://vuldb.com/?submit.601008>