High-Severity Memory Corruption Flaw Discovered in Python’s asyncio on Windows A critical security vulnerability (CVE-2026-3298) was disclosed on April 21, 2026, affecting Python’s asyncio module on Windows systems. The flaw, identified by Python security developer Seth Larson, enables out-of-bounds (OOB) memory writes in the `sock_recvfrom_into()` method of `asyncio.ProactorEventLoop`, a Windows-specific event loop for asynchronous I/O operations. The issue stems from a missing boundary check when the optional nbytes parameter is used. If network data exceeds the pre-allocated buffer size, Python fails to enforce limits, allowing excess data to overwrite adjacent memory. This can lead to memory corruption, application crashes, or under specific conditions arbitrary code execution. The vulnerability is exclusive to Windows, as other platforms (Linux, macOS, Unix) use the unaffected `SelectorEventLoop` backend. Systems at risk include Windows-hosted Python web servers, API backends, and applications using UDP socket operations or variable-length network data in fixed-size buffers. Given the widespread use of `ProactorEventLoop` as the default event loop since Python 3.8, the flaw impacts a broad range of modern Python deployments on Windows. The Python security team classified it as high severity, citing the potential for exploitation in memory corruption attacks. A patch (GitHub PR #148809) has been submitted, introducing the missing boundary check to prevent buffer overflows. Users are advised to monitor the official CVE record for patched version details and apply updates promptly. Until then, avoiding `sock_recvfrom_into()` with nbytes in untrusted environments is recommended.

GlassWorm Malware Campaign Exploits Stolen GitHub Tokens to Infect Python Repositories Security researchers at StepSecurity have uncovered an active malware campaign, dubbed GlassWorm, which is leveraging stolen GitHub tokens to inject malicious code into a wide range of Python repositories. The attack targets core project files including setup.py, main.py, and app.py across multiple Python ecosystems, such as Django applications, machine learning research code, Streamlit dashboards, and packages on the Python Package Index (PyPI). The campaign employs obfuscation techniques to evade detection, making it difficult for developers and security teams to identify compromised code. Once executed, the injected payload can enable remote access, facilitate data exfiltration, or further propagate the infection within connected networks and systems. Given Python’s widespread use in web development, data analytics, and scientific research, the attack poses significant risks to the integrity and security of applications built on these repositories. The primary entry point stolen GitHub tokens highlights the growing threat of supply chain attacks, where attackers exploit weak authentication controls to compromise trusted codebases. StepSecurity has confirmed the campaign’s ongoing activity, emphasizing the need for heightened vigilance in token management and code review processes to mitigate further exposure.

The Python Software Foundation (PyPI) was targeted in the GhostAction supply chain attack in early September 2023. Threat actors exploited malicious GitHub Actions workflows (e.g., FastUUID) to exfiltrate PyPI API tokens and other secrets (including npm, DockerHub, GitHub, Cloudflare, AWS, and database credentials) from over 570 repositories. While 3,300+ secrets were stolen across multiple ecosystems (Python, Rust, npm, JavaScript, Go), PyPI confirmed no evidence of token abuse to publish malware or compromise repositories. The attack leveraged stored GitHub secrets in workflows, sending them to attacker-controlled servers. Response delays occurred due to a spam-filtered alert from GitGuardian, postponing mitigation until September 10th. PyPI invalidated all affected tokens, urged maintainers to adopt short-lived Trusted Publishers tokens, and advised security reviews. Though no direct data breach or financial loss occurred, the incident exposed supply chain vulnerabilities, risking potential future exploits if unmitigated. The attack mirrored prior campaigns like s1ngularity (August 2023), highlighting persistent risks in open-source ecosystems.