(watchtowr.com) Citrix NetScaler CVE-2026-3055 Contains Multiple Memory Overread Vulnerabilities Including Active In-the-Wild Exploitation
Critical: CVE-2026-3055 in Citrix NetScaler actively exploited in-the-wild, leaking administrative session IDs via memory overreads in SAML/WS-Federation endpoints.
In brief - Unauthenticated attackers exploit CVE-2026-3055 to extract sensitive data, including authenticated admin session tokens, from vulnerable NetScaler appliances configured as SAML IDPs. Honeypot data confirms active exploitation by threat actors. Immediate patching required.
Technically - The flaw manifests in /wsfed/passive?wctx when the wctx parameter lacks a value, causing the appliance to dereference uninitialized memory. The NSC_TASS cookie returns base64-encoded leaked memory, exposing HTTP headers, internal IPs, and session IDs. Exploitation mirrors CitrixBleed techniques, with non-deterministic memory disclosure across requests. Patched systems return HTTP 302 without NSC_TASS. Detection artifacts available via watchTowr Labs.
Source: https://labs.watchtowr.com/please-we-beg-just-one-weekend-free-of-appliances-citrix-netscaler-cve-2026-3055-memory-overread-part-2/
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