Official MCP Python SDK Flaw Can Let Malicious Servers Steal OAuth Credentials

The Hacker News

September 29, 2026 at 6:08 AM

Overview

A vulnerability in the official MCP Python SDK allows attackers to create malicious servers that can trick applications into revealing OAuth credentials. This issue affects versions prior to 1.30.0, where sensitive information like the client secret, authorization code, and PKCE proof key could be sent to an attacker-controlled token endpoint. The SDK's maintainers have issued a security advisory regarding this flaw, emphasizing the risk it poses to applications relying on OAuth for authentication. Users of the affected SDK should update to version 1.30.0 or later to secure their applications against potential credential theft. This incident underscores the need for developers to stay vigilant about the libraries they use and the security implications they carry.

Key Takeaways

Affected Systems: MCP Python SDK versions prior to 1.30.0
Action Required: Update to MCP Python SDK version 1.
Timeline: Newly disclosed

Original Article Summary

A malicious MCP server could trick an application built on the official MCP Python SDK into handing over the OAuth credentials it uses to log in to a real service, the SDK's maintainers said in a security advisory. Affected versions sent the client secret, the authorization code, and the PKCE proof key to a token endpoint the attacker controlled. The fix is in versions 1.30.0 and

Impact

MCP Python SDK versions prior to 1.30.0

Exploitation Status

No active exploitation has been reported at this time. However, organizations should still apply patches promptly as proof-of-concept code may exist.

Timeline

Newly disclosed

Remediation

Update to MCP Python SDK version 1.30.0 or later.

Additional Information

This threat intelligence is aggregated from trusted cybersecurity sources. For the most up-to-date information, technical details, and official vendor guidance, please refer to the original article linked below.

Related Topics: This incident relates to Vulnerability, Update.

Read Original Article

Related Coverage

Hackers exploit Citrix NetScaler zero-day to deploy web shells

BleepingComputer

Cybersecurity experts have reported that attackers are exploiting a zero-day vulnerability in Citrix NetScaler, identified as CVE-2026-88772. This vulnerability allows hackers to deploy custom web shells and tunneling malware, which can lead to root access on affected systems. Once inside, attackers can steal credentials and move laterally across internal networks, posing a significant risk to organizations that rely on Citrix products. This incident is particularly concerning given the potential for widespread credential theft and internal network compromise. Organizations using Citrix NetScaler should take immediate action to assess their security posture and apply any available patches or mitigations.

Sep 29, 2026

Former US Air Force members sent to prison over BEC attacks

BleepingComputer

Two former members of the U.S. Air Force have been sentenced to a total of 189 months in federal prison for their involvement in a series of business email compromise (BEC) scams and phishing campaigns that spanned several years. These scams tricked businesses into transferring large sums of money by impersonating company executives or trusted partners through compromised email accounts. The actions of these individuals not only caused financial harm to various businesses but also highlighted the vulnerabilities in email communication systems. This case serves as a warning to organizations about the importance of email security and the need for robust verification processes to prevent similar attacks in the future.

Sep 29, 2026

Dual NetScaler Zero-Days Trigger Chaos for Citrix Customers

darkreading

Citrix customers are facing significant security risks due to two newly discovered zero-day vulnerabilities affecting their NetScaler products. These vulnerabilities allow attackers to gain unauthorized access to customer networks, essentially acting as a 'skeleton key.' The flaws are present in the default configurations of these products, which means many users may be at risk without any action taken. Given the critical nature of these vulnerabilities, organizations using NetScaler should prioritize assessing their configurations and implementing security measures to protect their networks. The urgency of this situation is underscored by the potential for active exploitation by malicious actors.

Sep 29, 2026

Kiteworks Fixes Critical Flaw Found During Nine-Hour Precautionary Shutdown

The Hacker News

Kiteworks announced that it discovered a critical security vulnerability during a scheduled precautionary shutdown, which took place over the weekend. The company collaborated with federal intelligence authorities to address the issue, which was confined to a feature used by less than 1% of their customer base. This vulnerability's existence raises concerns about the security of the affected systems, even though it's limited in scope. Kiteworks has not disclosed specific details about the vulnerability or the exact systems impacted, but the incident emphasizes the importance of regular security checks and timely responses to potential threats. Users of Kiteworks products should stay vigilant and ensure their systems are up to date with any patches released following this discovery.

Sep 29, 2026

Vietnamese man charged in $16 million 'pig butchering' crypto scam

BleepingComputer

A Vietnamese man is facing charges related to a large-scale cryptocurrency scam known as 'pig butchering,' which resulted in a staggering loss of $16 million for a victim. This scheme involved manipulating victims into investing in fake cryptocurrency platforms, leading to significant financial devastation. The term 'pig butchering' refers to the tactic of fattening up victims with false promises before taking their money. The case underscores the growing risks associated with cryptocurrency investments and the need for awareness about such scams. Victims of these scams often find it challenging to recover their funds, making this incident a stark reminder of the dangers in the digital currency space.

Sep 29, 2026

Kiteworks patches critical flaw, brings customer systems online

BleepingComputer

Kiteworks, an American tech company, recently addressed a significant security vulnerability that prompted them to advise customers to temporarily shut down their systems. The company has now released a patch to fix the flaw, allowing affected customer systems to come back online safely. This vulnerability could have exposed sensitive information, making the patching process crucial for maintaining data security. Users of Kiteworks' services were directly impacted, and the swift action taken by the company is essential to protect their clients from potential exploitation. Companies should ensure they apply the update promptly to mitigate any risks associated with this vulnerability.

Sep 29, 2026