CVE-2026-10856

Description

A URL validation flaw in the MISP dashboard button widget allowed a crafted relative-looking URL to be accepted as a local path while being interpreted by browsers as an external URL. The validation rejected URLs containing an explicit scheme, host, or user component, but did not reject paths beginning with a slash followed by a backslash, such as /\example.com. Some browsers normalize backslashes in URLs as forward slashes, which can turn this into a scheme-relative external navigation target. In addition, the generated href concatenated the reconstructed URL with the original URL, increasing the possibility of unsafe or malformed link generation. An attacker able to configure or influence a dashboard button URL could craft a button that appears to point inside the application but redirects users to an attacker-controlled site when clicked. This could be used for phishing, credential theft, or social engineering. The patch fixes the issue by rejecting empty paths and paths starting with /\, and by emitting only the reconstructed validated URL in the anchor href.

Is your site exposed to CVE-2026-10856?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

6.1

MEDIUM

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

EPSS — Exploit Prediction

0.0015

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-601 CWE-601

Affected Products

Vendor	Product	Versions
misp	misp	< 2.5.39

References

Advisories & Patches

https://github.com/MISP/MISP/commit/f879f16fb5db7a9aab0a70fdcafea12ce4847e9a

Frequently Asked Questions

What is CVE-2026-10856? +

A URL validation flaw in the MISP dashboard button widget allowed a crafted relative-looking URL to be accepted as a local path while being interpreted by browsers as an external URL. The validation rejected URLs containing an explicit scheme, host, or user component, but did not reject paths beginning with a slash followed by a backslash, such as /\example.com. Some browsers normalize backslashes in URLs as forward slashes, which can turn this into a scheme-relative external navigation target. In addition, the generated href concatenated the reconstructed URL with the original URL, increasing the possibility of unsafe or malformed link generation. An attacker able to configure or influence a dashboard button URL could craft a button that appears to point inside the application but redirects users to an attacker-controlled site when clicked. This could be used for phishing, credential theft, or social engineering. The patch fixes the issue by rejecting empty paths and paths starting with /\, and by emitting only the reconstructed validated URL in the anchor href. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2026-10856? +

CVE-2026-10856 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0015, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-10856? +

CVE-2026-10856 affects products from misp, specifically: misp. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-10856? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2024-53995

SickChill is an automatic video library manager for TV shows. A user-controlled `login` endpoint's `next_` parameter takes arbitrary content. Prior …

CVE-2026-40299

next-intl provides internationalization for Next.js. Applications using the `next-intl` middleware prior to version 4.9.1with `localePrefix: 'as-needed'` could construct URLs where …

CVE-2026-42350

Kargo manages and automates the promotion of software artifacts. Prior to versions 1.7.10, 1.8.13, 1.9.8, and 1.10.2, Kargo is vulnerable …

CVE-2026-10839

Open redirection vulnerability in the authentication system allows an attacker to use manipulated values in the X-Forwarded-Host header to alter …

CVE-2026-10837

Open redirection vulnerability due to insufficient validation of the X-Forwarded-Host HTTP header. An attacker could create manipulated links that, when …

CVE-2025-25300

smartbanner.js is a customizable smart app banner for iOS and Android. Prior to version 1.14.1, clicking on smartbanner `View` link …