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CVE-2026-1090 is a high-severity cross-site scripting vulnerability in GitLab Community Edition and Enterprise Edition. The flaw affects GitLab CE/EE versions from 10.6 before 18.7.6, 18.8 before 18.8.6, and 18.9 before 18.9.2. It is caused by improper sanitization of placeholder content during markdown processing when the markdown_placeholders feature flag is enabled. Under those conditions, an authenticated user can inject attacker-controlled JavaScript that executes in another user’s browser in the context of the GitLab application. The issue is classified as CWE-79.
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markdown_placeholders feature flag where operationally feasible, since the vulnerable condition requires that feature to be enabled. Limit access to authenticated users only as appropriate, monitor for suspicious markdown content and anomalous browser-side behavior in GitLab workflows, and prioritize expedited upgrade to a fixed release because no complete mitigation equivalent to patching is described.Patch, then assume compromise.
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No public exploit code observed for this vulnerability.
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12 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A high-severity cross-site scripting (XSS) vulnerability in GitLab Markdown placeholder processing (when the feature flag is enabled) that allows an authenticated attacker to bypass sanitization and inject malicious JavaScript into a victim’s browser.
An improper sanitization vulnerability in GitLab CE/EE markdown processing (when the `markdown_placeholders` feature flag is enabled) that could allow an authenticated user to inject JavaScript in a victim's browser (XSS).
A high-severity cross-site scripting vulnerability in GitLab CE/EE markdown placeholder processing that could let an authenticated user inject JavaScript when the markdown_placeholders feature flag is enabled.
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Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.