Microsoft is warning that attackers can hijack AI agents through poisoned tool descriptions, the plain-text notes that tell an agent what a tool does. Because agents connect to systems through the Model Context Protocol and read these descriptions to decide how to act, an attacker who updates a trusted third-party tool can bury a hidden instruction in its description, telling the agent to quietly collect and exfiltrate data on its next task. Many setups pick up description changes without re-approval, so the poisoned version goes live silently. Each step the agent takes looks legitimate and runs with the user's own permissions, so no alarm fires.
Wiz Research found a high-severity flaw in Amazon Q Developer, Amazon's AI coding assistant, that let a malicious code repository run commands and steal a developer's cloud credentials simply by being opened. The bug (CVE-2026-12957) lay in how Amazon Q handled Model Context Protocol servers: it read an MCP configuration file from the open workspace and automatically launched the servers it defined. Because those servers run as local processes that inherit the developer's full environment, a single config file committed to a repo could reach AWS keys, cloud tokens, API secrets, and SSH agent sockets, turning a git clone into a full compromise. Amazon has patched the issue and published an advisory.
Researchers at Tenet Security have disclosed Agentjacking, a new attack that turns AI coding assistants like Claude Code, Cursor, and Codex into tools for running an attacker's code on a developer's machine. The trick abuses Sentry, a widely used error-tracking service: anyone can submit a fake error event using a project's DSN, a public write-only key embedded in website code, and the AI agent, fetching that event through Sentry's MCP integration, cannot tell the malicious instructions from real diagnostics and runs them with the developer's privileges. No phishing, malware, or server breach is needed, and it bypasses traditional controls because every step is technically authorized. Tenet found 2,388 exposed organizations.
TeamPCP's self-propagating supply-chain worm is back in its third iteration, branded 'Shai-Hulud: The Third Coming' in hard-coded strings across the malware. On April 22, Socket reported Checkmarx's official KICS Docker images and a KICS VS Code / Open VSX extension had been trojanized. Bitwarden's own clients repo runs a Checkmarx scan on every pull request via a pull_request_target workflow that holds id-token: write and fetches credentials from Azure Key Vault, so when the poisoned scanner executed it harvested GitHub OIDC and Azure tokens. At 17:57 ET the same day, attackers used those tokens to push a modified publish-cli.yml to the Bitwarden repo and publish a malicious @bitwarden/cli version 2026.4.0 to npm. The package remained live for 93 minutes until Bitwarden pulled it at 19:30 ET. The payload: a 10MB obfuscated credential harvester that grabs SSH keys, cloud provider credentials, npm publish tokens, GitHub tokens, and - new in this variant - MCP (Model Context Protocol) configuration files used by Claude Code, Cursor, and similar AI coding tools. It then self-propagates by republishing into every npm package the victim can modify and uploads encrypted stolen secrets to public GitHub repositories under Dune-themed names. The worm has a Russian-locale kill switch (exits if LC_ALL/LANG starts with 'ru').
Backfill from April 15: OX Security disclosed an architectural flaw in the official Model Context Protocol SDKs (Python, TypeScript, Java, Rust) that lets attacker-controlled JSON config trigger arbitrary OS commands via the STDIO transport. Roughly 200,000 publicly reachable MCP servers and 150 million SDK downloads inherit the issue. OX has tied 14 CVEs to the same root cause across LiteLLM (patched), Bisheng (patched), Windsurf (zero-click RCE in Cursor-style IDEs, still reported), Flowise, LangFlow, GPT Researcher, Agent Zero, and DocsGPT. Anthropic declined to patch the protocol, calling the behavior 'expected.'
A CVSS 9.8 authentication bypass in nginx-ui, the popular open-source web management interface for Nginx servers, is being actively exploited in the wild. The flaw, codenamed MCPwn by Pluto Security, exists because the /mcp_message endpoint added for Model Context Protocol (AI integration) support only checks IP whitelisting - and the default whitelist is empty, meaning it allows all connections. One unauthenticated HTTP POST request lets an attacker invoke all MCP tools: rewrite Nginx config files, reload the server, intercept all traffic, and harvest admin credentials. Attackers chain it with CVE-2026-27944 (exposed encryption keys via the backup API) to extract the node_secret needed for full MCP access. Recorded Future flagged active exploitation and assigned a risk score of 94/100. Shodan shows 2,600 publicly exposed instances, mostly in China, the US, Indonesia, and Germany. Pluto Security's key lesson: AI integration endpoints expose the same capabilities as the core application but often skip its security controls.
TrustStrike Labs