Loading vulnerability…
CVE-2026-62899 is a security feature bypass vulnerability in .NET caused by inconsistent interpretation of HTTP requests between a frontend reverse proxy and a backend .NET application. The issue affects deployment scenarios in which the .NET backend is hosted on Linux or macOS behind an affected reverse proxy. Exploitation uses HTTP request smuggling techniques, including CL.TE or TE.CL desynchronization, to create parser disagreement over request boundaries. In the described CL.TE case, the frontend proxy processes the request according to Content-Length while the backend .NET parser normalizes a malformed Transfer-Encoding header and interprets the body as chunked data. After the backend reaches the terminating chunk, residual bytes on the same TCP connection are parsed as a second, attacker-controlled request. This can cause the backend to process a smuggled request that was not subject to the frontend proxy's intended security checks. Referenced affected components include System.Net.HttpListener and related .NET runtime handling of HTTP parsing.
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
If you can’t patch tonight, do this now.
Patch, then assume compromise.
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
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.
10 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An HTTP request smuggling vulnerability affecting .NET backend applications on Linux or macOS when deployed behind an affected frontend reverse proxy, caused by inconsistent parsing of malformed Transfer-Encoding headers between the proxy and the backend.
.NET Security Feature Bypass vulnerability.
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.