The first bug is tracked as CVE-2026-23863, a Windows specific problem. This bug was maliciously crafted with hidden “NUL BYTES” hidden within the filename, to trick WhatsApp into showing it as one filetype such as an authorized PDF while pretending to be running as an executable once opened. Meta fixed this patch in April on both platforms.
The second vulnerability, tracked as CVE-2026-23866 impacted both android and iOS users. The attack tactic involved partial authorization of AI rich response texts for Instagram Reels shared within Whatsapp. A threat actor could possible launch another user’s device to access media content through an arbitrary URL, such as launching OS level custom URL scheme handles. This flaw was patched in April on both platforms.
The two bugs were given medium severity by researchers. WhatsApp has verified that no bug was abused.
Both were rated medium severity, and WhatsApp confirmed there's no evidence either was actually abused.
These kind of reporting get sidelined by glossy and infamous threat. For instance the recent SMS pumpoing attacks increasing phone bills, or phishing campaigns that used messaging apps as entry points, and lastly the attack on educational institutes that compromised Canvas and Instructure, leaking hundreds of GBs of data.
But Whatsapp did a good job in finding and fixing the flaw before cybercriminals could exploit them and cause harm. The bug bounty program of WhatsApp has been going on for fifteen yesr, and the recent patches show it it is still reliable.
Simple advice: always keep your phones and app updated.
There has never been a better moment to use secure communications services like WhatsApp or Signal. The truth is that Meta does a great job of keeping the app and its users safe and secure, despite some security concerns of its own, such as the recently reported phishing attempts using the encrypted messenger as part of the exploit chain and a spyware threat targeting iOS users.
Security researchers have uncovered a gap in the way Anthropic Skill scanning tools inspect third-party AI packages, allowing malicious code hidden inside test files to execute on developer systems even after scanners marked the Skills as safe.
The issue centers on Anthropic Skills, reusable packages designed for AI coding assistants such as Claude Code, Cursor, and Windsurf. These packages often include instructions, scripts, and configuration files that help AI agents perform development tasks inside IDE environments.
Researchers from Gecko Security found that existing Skill scanners focus primarily on files tied directly to agent behavior, particularly SKILL.md, while ignoring bundled test files that can still run locally through standard developer tooling.
In the demonstrated attack chain, a Skill passed all scanner checks because its visible instruction files contained no prompt injection attempts, suspicious shell commands, or malicious instructions. However, the repository also included a hidden .test.ts file stored elsewhere in the directory structure. Although the file was outside the agent execution layer, it still executed through the project’s testing framework with full access to local resources.
According to researcher Jeevan Jutla, the problem begins when developers install a Skill using the npx skills add command. The installer copies nearly the entire repository into the project’s .agents/skills/ directory. Only a few items, including .git, metadata.json, and files prefixed with underscores, are excluded during installation.
Once placed inside the repository, testing frameworks such as Jest and Vitest automatically discover matching test files through recursive glob patterns. Both frameworks reportedly enable the dot:true option, allowing them to search inside hidden directories including .agents/. Mocha follows similar recursive discovery behavior in many default configurations.
A malicious Skill can therefore include a file such as reviewer.test.ts containing a beforeAll function that silently executes before visible tests begin. Researchers said these payloads can access environment variables, .env files, SSH keys, AWS credentials, deployment tokens, and other sensitive information commonly available inside local developer environments and CI pipelines. The data can then be transmitted to external servers without triggering obvious warnings during test execution.
The researchers stressed that the AI agent itself is never involved in the compromise. Instead, the malicious behavior occurs through trusted developer tooling already integrated into the software workflow. Existing scanners inspect the files the AI agent can interpret, but not the files executed separately by testing infrastructure.
The technique resembles older software supply-chain attacks involving malicious npm postinstall scripts and poisoned pytest plugins. However, Gecko Security noted that the Anthropic Skill ecosystem creates an additional propagation problem because installed Skills are often committed into shared repositories so teams can reuse them collaboratively.
GitHub’s default .gitignore templates do not automatically exclude .agents/ directories. Once a malicious test file enters the repository, every teammate cloning the project and every CI pipeline running automated tests may execute the payload across branches, forks, and deployment workflows.
The findings arrived shortly after multiple large-scale security audits examining the broader Anthropic Skills ecosystem. A January academic study named SkillScan analyzed 31,132 Skills collected from two major marketplaces and found that 26.1% contained at least one vulnerability spanning 14 separate patterns. Data exfiltration appeared in 13.3% of examined Skills, while privilege escalation appeared in 11.8%. Researchers also determined that Skills bundling executable scripts were 2.12 times more likely to contain vulnerabilities than instruction-only packages.
Several weeks later, Snyk published its ToxicSkills audit covering 3,984 Skills from ClawHub and skills.sh. The company reported that 13.4% of scanned Skills contained at least one critical-level security issue. Automated analysis combined with human review identified 76 confirmed malicious payloads, while eight malicious Skills reportedly remained publicly accessible on ClawHub when the findings were released.
In April, Cisco introduced an AI Agent Security Scanner integrated into IDE platforms including VS Code, Cursor, and Windsurf. The scanner can detect prompt injection attempts, suspicious shell execution patterns, and data exfiltration behaviors within Skill definitions and agent-referenced scripts. However, Gecko Security said bundled test files remain outside the scanner’s documented detection surface because the tool was designed around agent interaction layers rather than developer execution layers.
Researchers noted that other products, including Snyk Agent Scan and VirusTotal Code Insight, face similar structural limitations. These tools inspect what the agent is instructed to execute but may overlook code paths triggered separately through local development frameworks.
Elia Zaitsev described the broader issue as a distinction between interpreting intent and monitoring actual execution behavior. In this case, the malicious code did not depend on prompt manipulation or AI instructions. It operated as ordinary TypeScript executed through legitimate test runners with full local permissions.
Zaitsev also warned that enterprise AI agents increasingly operate with privileged access to OAuth tokens, API keys, and centralized data sources. If those credentials are accessible through environment variables during automated testing, malicious test payloads can reach sensitive infrastructure without requiring direct agent compromise.
Mike Riemer added that threat actors frequently reverse engineer security patches within 72 hours of release, while many organizations take far longer to deploy fixes. In the case of the Anthropic Skill test-file issue, researchers warned that the exposure window becomes more difficult to manage because the malicious files may execute immediately after installation without triggering scanner alerts.
Security researchers are urging development teams to block test discovery inside .agents/ directories and inspect Skill repositories for files such as *.test.*, *.spec.*, conftest.py, __tests__/, and suspicious configuration scripts before merging code.
The report also recommends pinning Skill installations to verified commit hashes rather than installing the latest repository version. Researchers said this reduces the risk of attackers submitting clean repositories for scanner approval before later inserting malicious files. The approach aligns with guidance published in the OWASP Agentic Skills Top 10 project.
Organizations that already store Skills inside repositories are advised to audit existing .agents/ directories immediately, rotate exposed credentials if suspicious files are discovered, inspect CI logs for unexplained outbound network traffic, and review repository history to identify when potentially malicious files entered development pipelines.
The researchers additionally called on security vendors to provide greater transparency regarding which directories, execution surfaces, and file categories their scanners actually inspect. They argued that security teams evaluating Anthropic Skill scanners should verify whether products analyze bundled test files, build scripts, and CI configurations rather than focusing exclusively on prompt injection and agent instruction analysis.
Password theft operations continue to expand despite growing public awareness campaigns around online security. Infostealer malware remains active, compromised accounts continue circulating across underground marketplaces, and stolen credentials are still being used for financial fraud, ransomware attacks, and unauthorized access to online services.
New research published by Comparitech examined how stolen passwords move through cybercriminal networks after they are first compromised. The study analyzed more than 447,000 credential leaks, breach threads, and password dumps posted across four major cybercrime forums. Altogether, the dataset contained roughly 1.1 million compromised user records collected between 2013 and 2026.
The report focused on understanding where leaked passwords ultimately end up and how attackers process them before they are used in large-scale attacks.
For many users, discovering that a password has been exposed can create immediate panic, particularly because credential theft incidents have increased sharply in recent years. Previous security reporting found that nearly 2.8 billion credentials were exposed during 2025 alone. Researchers have also raised concerns about browser-stored passwords after reports that credentials saved in browsers may sometimes become accessible in plaintext form within system memory. At the same time, stolen credentials are increasingly being used to abuse retail, cloud, and subscription-based services.
According to Comparitech researcher Paul Bischoff, analysts including Mantas Sasnauskas reviewed databases from four cybercrime forums to understand how stolen passwords are accessed, redistributed, combined, and eventually weaponized in credential-stuffing campaigns, ransomware intrusions, business email compromise incidents, and account takeover attacks.
The researchers outlined a five-stage credential supply chain. The first stage, known as “origin,” refers to how passwords are initially stolen before appearing on underground forums. The report identified infostealer malware and data breaches as the two most common starting points.
Infostealer malware is designed to silently collect sensitive information from infected devices. This can include browser-saved passwords, authentication cookies, autofill data, cryptocurrency wallet information, and session tokens that attackers can later exploit to bypass login protections.
The final stage of the supply chain involves the eventual use of stolen credentials in attacks such as ransomware deployment, unauthorized account access, and corporate breaches. However, the researchers said the middle stages of the ecosystem reveal the most about how the underground password economy functions.
The wholesale stage represents the broker market for stolen access. In this phase, attackers sell compromised credentials directly to other criminals. The report pointed to the Russian-language cybercrime forum RAMP, where pre-authenticated access to corporate systems was allegedly being offered for sale using stolen login credentials. This type of access is especially valuable because it can provide immediate entry into business networks.
The next stage, trade, involves credentials being reposted, exchanged, resold, or distributed across multiple hacker forums. Some datasets are uploaded for free to build credibility inside underground communities, while others are placed behind paid marketplaces where buyers can purchase access to larger credential collections.
The aggregation stage centers around the creation of “combolists,” which are massive databases containing usernames and passwords collected from multiple breaches. The most valuable combolists are typically cleaned and deduplicated to remove repeated records and improve their effectiveness.
Attackers frequently use these combolists in credential-stuffing operations, where automated tools test stolen username-and-password combinations across many different websites. Because many users reuse passwords across platforms, one compromised credential can sometimes unlock email accounts, banking services, shopping platforms, or workplace systems tied to the same login information.
Researchers and cybersecurity analysts have repeatedly warned that the underground market for stolen credentials continues growing alongside the rise of malware-as-a-service operations and initial access brokers. In recent years, infostealer logs containing browser credentials and authentication cookies have become widely traded across dark web forums and encrypted messaging platforms.
The report also examined how users can reduce the risk of credential theft. Security professionals continue encouraging users to adopt passkeys whenever possible because passwordless authentication systems are significantly harder to steal and reuse in automated attacks.
Experts additionally recommend avoiding password reuse across websites and services, since a single breach can otherwise expose multiple accounts at once. Password managers can help users generate and store unique credentials securely, while two-factor authentication adds another layer of verification that can block unauthorized logins even if a password becomes compromised.
As cybercrime groups continue refining credential theft operations, researchers believe password-based security systems may gradually become less reliable for protecting online accounts in the long term.
The incident is improper privilege management that could have allowed threat actors to reveal sensitive data as unprivileged local users and launch arbitrary commands on default installs such as Ubuntu, Debian, and Fedora. Its alias is aka ssh-keysign-pwn.