Code injection RCE in Microsoft Defender for Linux (Defender for Endpoint Linux extension)
CVE-2026-21537 is an improper control of generation of code (code injection) vulnerability in Microsoft Defender for Linux (Microsoft Defender for Endpoint Linux extension). The issue allows an unauthorized attacker to achieve code execution over an adjacent network. The CVSS v3.1 vector is AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, indicating low attack complexity, no privileges or user interaction required, and high impact to confidentiality, integrity, and availability.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
11 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A remote code execution vulnerability affecting Microsoft Defender for Endpoint Linux Extension.
A vulnerability affecting Microsoft Defender for Linux; specific impact type not provided in the content.
A remote code execution vulnerability in Microsoft Defender for Endpoint Linux Extension (Microsoft Defender for Linux).
A code injection vulnerability (CWE-94) in Microsoft Defender for Linux that could allow unauthorized code execution from an adjacent network.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.