Anthropic

Claude Mythos Unauthorized Access Exposes AI Security

ATLAS OWASP HIGH ▲ 7.2 The Hacker News Jun 08, 2026

A reported unauthorized access to Anthropic's Claude Mythos model within hours of its limited technical preview highlights acute security risks as agentic AI is deployed across classified defense and intelligence networks. The incident underscores vulnerabilities specific to AI infrastructure in high-security environments, including training data poisoning, access control failures, and cross-domain classification boundary erosion. Secure IT infrastructure, governed access, and cross-domain data controls are identified as prerequisites for safe AI deployment at mission scale.

Claude Sandbox Escape Enables Credential Exfiltration

ATLAS OWASP MEDIUM ▲ 7.2 Simon Willison May 31, 2026

Anthropic has published detailed documentation of its sandboxing architecture across Claude.ai, Claude Code, and Claude Cowork, including disclosure of a previously identified credential exfiltration vector via the api.anthropic.com/v1/files endpoint. The writeup covers process-level isolation technologies including gVisor, Seatbelt, Bubblewrap, and full VM approaches, and candidly acknowledges security gaps that were missed. This transparency is notable for the agentic AI space, where sandbox documentation is typically sparse and trust is difficult to calibrate.

mouse5212-super-formatter npm Malware Steals Claude Files

ATLAS OWASP HIGH ▲ 8.2 The Hacker News May 29, 2026

A malicious npm package named 'mouse5212-super-formatter' was discovered exfiltrating files from Anthropic's Claude AI user directory by authenticating to a threat actor-controlled GitHub repository. The package disguised itself as a legitimate archive utility while silently uploading all local workspace files during the postinstall phase. Notably, the attacker's poor operational security — including a leaked GitHub token — suggests AI-generated malware with minimal human oversight, pointing to a growing trend of low-skill threat actors leveraging AI to produce supply chain malware.

CVE-2026-5194: Anthropic Claude Discovers 10,000+ Flaws

ATLAS OWASP HIGH ▲ 8.5 The Hacker News May 25, 2026

Anthropic's Project Glasswing has deployed Claude Mythos Preview — a frontier AI model — to autonomously discover over 10,000 high- and critical-severity vulnerabilities across widely used open-source software, with 1,094 confirmed as valid high/critical flaws. The initiative highlights a growing asymmetry: AI is accelerating vulnerability discovery far faster than the security community can remediate, compressing patch windows and raising the stakes for defenders. Anthropic is now urging shorter patch cycles and hardened defaults, warning that comparable offensive capabilities could soon be broadly accessible to threat actors.

Mythos AI Exploits macOS Kernel Memory Corruption

ATLAS OWASP HIGH ▲ 7.5 Schneier on Security May 22, 2026

A threat group leveraged Anthropic's Mythos AI model to identify and exploit a kernel memory corruption vulnerability in Apple's M5 chip running macOS. This represents a concrete, reported instance of AI-assisted vulnerability research being used offensively to discover low-level hardware-adjacent exploits. The incident underscores the dual-use danger of increasingly capable AI coding and reasoning models in the hands of adversarial actors.

Claude Chrome Extension Prompt Injection Enables Agent Takeover

ATLAS OWASP HIGH ▲ 9.1 SecurityWeek May 09, 2026

A vulnerability dubbed ClaudeBleed in Anthropic's Claude Chrome extension allows any browser extension to inject arbitrary prompts into the Claude AI agent by exploiting lax permission checks and improper trust validation. Attackers can bypass user confirmation protections via DOM manipulation and repeated message forging, enabling full agent takeover for information theft or unauthorized actions. The flaw effectively breaks Chrome's extension security model and exposes users running Claude's agentic capabilities to third-party extension compromise.

Firefox Vulnerabilities Discovered via AI-Assisted Fuzzing

ATLAS OWASP HIGH ▲ 7.2 Simon Willison May 08, 2026

Mozilla used early access to Anthropic's Claude Mythos model to systematically discover and patch hundreds of previously unknown vulnerabilities in Firefox, including bugs over 15–20 years old. The effort demonstrates a step-change in AI-assisted vulnerability research, with April 2026 seeing 423 security fixes compared to a monthly baseline of 20–30. The same capability that empowered Mozilla's defenders also signals that adversaries with similar model access could industrialise exploit discovery against open-source software at scale.

Claude Code OAuth Token Theft via npm Supply Chain

ATLAS OWASP HIGH ▲ 9.1 SecurityWeek May 08, 2026

Mitiga Labs has disclosed a stealthy attack chain targeting Claude Code's MCP infrastructure, allowing adversaries to silently intercept OAuth tokens by redirecting MCP traffic through attacker-controlled infrastructure. The attack requires only the ability to install a malicious npm package, which modifies ~/.claude.json to insert a proxy and pre-sets trust flags to suppress security prompts. Because the OAuth token grants broad access to all connected SaaS tools, successful exploitation effectively hands attackers a persistent master key to the victim's integrated development environment.

Anthropic Releases Claude Security Vulnerability Scanner

ATLAS OWASP HIGH ▲ 7.2 SecurityWeek May 01, 2026

Anthropic has released Claude Security in public beta, a dedicated vulnerability scanning product aimed at countering the accelerating threat of AI-powered exploitation exemplified by its own Mythos model. The tool integrates directly into Claude Enterprise, scanning repositories for vulnerabilities, providing confidence-rated findings, and generating targeted patches — compressing the security team-to-engineer remediation cycle from days to a single session. The launch reflects a broader industry acknowledgment that frontier AI models in adversarial hands are fundamentally shortening time-to-exploit, forcing defenders to adopt equivalent AI-native tooling.

GPT-5.5 Matches Claude Mythos in Vulnerability Discovery

ATLAS OWASP HIGH ▲ 7.2 Simon Willison May 01, 2026

The UK's AI Security Institute has evaluated OpenAI's GPT-5.5 for offensive cybersecurity capabilities, finding it comparable to Anthropic's Claude Mythos model in identifying security vulnerabilities. Unlike Mythos, GPT-5.5 is generally available, meaning its vulnerability-discovery capabilities are accessible to a broad population including malicious actors. This raises significant concerns about the proliferation of AI-assisted exploitation tools at scale.

CVE-2026-42208: LiteLLM SQL Injection Exposes API Keys

ATLAS OWASP CRITICAL ▲ 9.2 The Hacker News Apr 30, 2026

A critical SQL injection vulnerability (CVE-2026-42208, CVSS 9.3) in BerriAI's LiteLLM AI gateway was actively exploited within 36 hours of public disclosure, targeting database tables storing upstream LLM provider API keys including OpenAI, Anthropic, and AWS Bedrock credentials. Attackers demonstrated prior knowledge of LiteLLM's internal schema, selectively probing credential and configuration tables while ignoring user and team tables. The blast radius extends far beyond a typical web-app SQL injection, as successful extraction equates to cloud-account-level compromise across multiple AI provider accounts.

CVE-2026-42208: LiteLLM SQL Injection Stealing AI Credentials

ATLAS OWASP CRITICAL ▲ 9.2 BleepingComputer Apr 29, 2026

A critical unauthenticated SQL injection vulnerability (CVE-2026-42208) in LiteLLM, a widely-used LLM proxy and SDK middleware, is being actively exploited to extract API keys, provider credentials, and configuration secrets from the proxy database. Exploitation began within 36 hours of public disclosure, with attackers demonstrating precise targeting of sensitive tables containing OpenAI, Anthropic, and Bedrock credentials. The stolen credentials could enable downstream attacks against AI infrastructure at scale, given LiteLLM's broad adoption across LLM application ecosystems.

Anthropic Mythos Preview Breached via Contractor Credentials

ATLAS OWASP HIGH ▲ 8.2 Wired Security Apr 26, 2026

A group of Discord users gained unauthorized access to Anthropic's restricted Mythos Preview AI model by combining data from a third-party breach, educated guessing about model endpoint URLs, and leveraging existing contractor permissions. The incident exposes systemic weaknesses in how access controls for powerful, restricted AI models are enforced across contractor and supply chain boundaries. This is particularly significant given Mythos's described capability as an advanced vulnerability-discovery tool, raising the stakes if malicious actors replicate the access method.

Anthropic Claude Memory Poisoning Enables Prompt Injection

ATLAS OWASP HIGH ▲ 8.2 Dark Reading Apr 24, 2026

Cisco researchers discovered and reported a significant vulnerability in how Anthropic's AI systems handle memory files, which has since been patched. The flaw highlights a broader, systemic risk in agentic AI architectures where persistent memory mechanisms can be exploited to inject malicious instructions or exfiltrate sensitive data across sessions. Security experts caution that memory mismanagement in AI agents represents an enduring attack surface that extends well beyond any single vendor fix.

Anthropic Mythos AI Achieves 72% Autonomous Exploit Success

ATLAS OWASP CRITICAL ▲ 9.2 The Hacker News Apr 24, 2026

Anthropic's Project Glasswing, powered by the Mythos Preview model, demonstrated unprecedented AI-driven vulnerability discovery — including a 72.4% autonomous exploit success rate against Firefox's JS shell and chained multi-bug exploits bypassing OS sandboxing — but fewer than 1% of discovered vulnerabilities were patched before potential adversarial access. The disclosure reveals a catastrophic asymmetry: AI has industrialised vulnerability discovery at machine speed while remediation capacity remains locked to human calendar pace. Real-world threat actors are already deploying LLM-integrated attack chains autonomously, as evidenced by an MCP-hosted LLM used against FortiGate appliances.

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