EmilStenstrom justhtml up to 1.12.x to_markdown cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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5.1$0-$5k2.15

Summaryinfo

A vulnerability, which was classified as problematic, was found in EmilStenstrom justhtml up to 1.12.x. This affects the function to_markdown. Such manipulation leads to cross site scripting. This vulnerability is referenced as CVE-2026-5389. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in EmilStenstrom justhtml up to 1.12.x. It has been rated as problematic. Affected by this issue is the function to_markdown. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. CVE summarizes:

justhtml versions before 1.13.0 contain a cross-site scripting vulnerability in the to_markdown() function when serializing attacker-controlled pre content. Attackers can place backticks inside sanitized pre elements to break out of fixed-length code fences, allowing raw HTML to execute when the generated Markdown is rendered by CommonMark or GFM-style renderers.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-5389 since 04/01/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project.

Upgrading to version 1.13.0 eliminates this vulnerability.

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Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.2
VulDB Meta Temp Score: 5.1

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.1
CNA Vector (VulnCheck): 🔒

CVSSv2info

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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: justhtml 1.13.0

Timelineinfo

04/01/2026 CVE reserved
08/23/2026 +144 days Advisory disclosed
08/23/2026 +0 days VulDB entry created
08/23/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-5389 (🔒)
GCVE (CVE): GCVE-0-2026-5389
GCVE (VulDB): GCVE-100-394550

Entryinfo

Created: 08/23/2026 15:59
Changes: 08/23/2026 15:59 (76)
Complete: 🔍
Cache ID: 216::103

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