Altair: DOM-based XSS via attacker-controlled script URLs in the iframe sandbox

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-110802: 0.22% estimated exploitation activity in the next 30 days; percentile 12.75 (FIRST EPSS, 2026-11-10). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Altair `8.5.7` accepts plugin configuration directly from the `iframe-sandbox` query string. When `plugin_sandbox_opts` contains `type: "scripts"` and an attacker-controlled URL in `scriptUrls`, the sandbox page creates a classic ` ` element and loads the supplied script. In the intended plugin flow, this page runs inside an ` ` without `allow-same-origin`, giving plugin code an opaque origin. However, if a victim opens the crafted sandbox URL directly, that iframe isolation is absent and the attacker-controlled script executes in the origin serving Altair, resulting in DOM-based cross-site scripting (XSS) / arbitrary JavaScript execution in the Altair hosting origin. Exploitation requires the victim to open a crafted URL.

Details The sandbox reads its configuration directly from `window.location.search`. In `packages/altair-iframe-sandbox/src/main.ts`: ``` const searchParams = new URLSearchParams(window.location.search); const sandboxType =…

Published by the source

10 Nov 2026, 15:57 UTC

Last modified by the source

10 Nov 2026, 16:15 UTC

Source last checked

11 Nov 2026, 06:00 UTC

1. Revision 2 · amended · 11 Nov 2026

   Amended from osv record GHSA-752m-7p75-49gf

2. Revision 1 · created · 10 Nov 2026

   Published from ghsa record GHSA-752m-7p75-49gf

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# Patch Next advisory brief: CVE-2026-110802

Advisory: Altair: DOM-based XSS via attacker-controlled script URLs in the iframe sandbox
IDs: CVE-2026-110802, GHSA-752m-7p75-49gf
Record: https://patchnext.com/advisories/cve-2026-110802 (revision 2, source checked 11 Nov 2026, 06:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: altair-static 8.5.8; altair-express-middleware 8.5.8; altair-fastify-plugin 8.5.8; altair-koa-middleware 8.5.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm altair-static: affected >= 7.2.4, < 8.5.8; fixed in 8.5.8
- npm altair-express-middleware: affected >= 7.2.4, < 8.5.8; fixed in 8.5.8
- npm altair-fastify-plugin: affected >= 7.2.4, < 8.5.8; fixed in 8.5.8
- npm altair-koa-middleware: affected >= 7.2.4, < 8.5.8; fixed in 8.5.8

## Suggested inspection (read-only)
- `npm ls altair-static --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls altair-express-middleware --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls altair-fastify-plugin --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls altair-koa-middleware --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on altair-static, altair-express-middleware, altair-fastify-plugin, altair-koa-middleware.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-752m-7p75-49gf (GitHub-reviewed advisory GHSA-752m-7p75-49gf lists affected ranges: npm altair-static >=7.2.4 =7.2.4 =7.2.4 =7.2.4 <8.5.8)
- Verified: https://osv.dev/vulnerability/GHSA-752m-7p75-49gf (OSV record GHSA-752m-7p75-49gf lists affected ranges: npm altair-static >=7.2.4 =7.2.4 =7.2.4 =7.2.4 <8.5.8 (fixed))

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