CVE-2025-26619: vega XSS — Exploit & Fix

Description

Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs. In `vega` 5.30.0 and lower and in `vega-functions` 5.15.0 and lower , it was possible to call JavaScript functions from the Vega expression language that were not meant to be supported. The issue is patched in `vega` `5.31.0` and `vega-functions` `5.16.0`. Some workarounds are available. Run `vega` without `vega.expressionInterpreter`. This mode is not the default as it is slower. Alternatively, using the interpreter described in CSP safe mode (Content Security Policy) prevents arbitrary Javascript from running, so users of this mode are not affected by this vulnerability.

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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

Weakness Type (CWE)

CWE-79 Cross-site Scripting (XSS)

Affected Products

Vendor	Product	Versions
vega-functions_project	vega-functions	< 5.16.0
vega_project	vega	< 5.31.0

References

Advisories & Patches

https://github.com/vega/vega/commit/8fc129a6f8a11e96449c4ac0f63de0e5bfc7254c https://github.com/vega/vega/security/advisories/GHSA-rcw3-wmx7-cphr https://github.com/vega/vega/security/advisories/GHSA-rcw3-wmx7-cphr

Exploits

https://github.com/vega/vega/issues/3984 https://github.com/vega/vega/security/advisories/GHSA-rcw3-wmx7-cphr https://github.com/vega/vega/security/advisories/GHSA-rcw3-wmx7-cphr

Other References

https://github.com/vega/vega-lite/issues/9469

Frequently Asked Questions

What is CVE-2025-26619? +

Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs. In `vega` 5.30.0 and lower and in `vega-functions` 5.15.0 and lower , it was possible to call JavaScript functions from the Vega expression language that were not meant to be supported. The issue is patched in `vega` `5.31.0` and `vega-functions` `5.16.0`. Some workarounds are available. Run `vega` without `vega.expressionInterpreter`. This mode is not the default as it is slower. Alternatively, using the interpreter described in CSP safe mode (Content Security Policy) prevents arbitrary Javascript from running, so users of this mode are not affected by this vulnerability. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2025-26619? +

CVE-2025-26619 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.

What products are affected by CVE-2025-26619? +

CVE-2025-26619 affects products from vega-functions_project, vega_project, specifically: vega, vega-functions. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-26619? +

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.

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