CVE-2026-112063 in libstrophe
Summary
by MITRE • 10/18/2026
libstrophe through 0.14.0 contains a stack-based buffer overflow vulnerability in SCRAM_Hi that allows malicious XMPP servers to overflow a 128-byte stack buffer by sending an oversized SCRAM salt. Attackers can send a server-first-message whose s= attribute decodes to more than 124 bytes, aborting the client or overwriting stack memory in NDEBUG builds.
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Analysis
by VulDB Data Team • 10/18/2026
The vulnerability identified within libstrophe versions up to and including 0.14.0 represents a critical security flaw rooted in improper input validation during the processing of SCRAM authentication mechanisms. Specifically, the defect resides in the SCRAM_Hi function, which is responsible for handling high-level cryptographic operations associated with the Salted Challenge Response Authentication Mechanism used in XMPP communications. This stack-based buffer overflow occurs when the library processes a server-first-message from an untrusted or malicious XMPP server. The core technical failure involves the s= attribute within this message, which contains the salt value required for password verification. When this attribute decodes to a length exceeding 124 bytes, it triggers a write operation that surpasses the boundaries of a fixed-size 128-byte stack buffer allocated by the application. This miscalculation fails to account for necessary null terminators or overhead, leading directly to memory corruption on the call stack.
From an operational perspective, this vulnerability allows remote attackers who control or can manipulate the XMPP server endpoint to execute arbitrary code or cause a denial of service against the client application. In standard builds where assertions are enabled, the overflow may be detected and result in an immediate abort, effectively crashing the client process and disrupting communication services. However, in production environments compiled with NDEBUG flags, which disable runtime checks for performance optimization, the consequences are far more severe. The attacker can overwrite adjacent stack memory, potentially overwriting return addresses or other critical control data structures. This capability enables the execution of arbitrary machine code within the context of the vulnerable application, granting the attacker full control over the client system. Such exploitation could lead to unauthorized access to sensitive communications, credential theft via keylogging if injected into input handlers, or further lateral movement within a networked environment relying on XMPP for messaging and presence services.
The technical classification of this flaw aligns with CWE-121, which denotes a stack-based buffer overflow caused by copying user-controlled data without adequate bounds checking. This type of vulnerability is particularly dangerous because it exploits the fundamental memory management assumptions made by compiled languages like C or C++. The attack vector corresponds to ATT&CK technique T1059, specifically command and script interpretation if code execution is achieved, or more broadly under initial access vectors where a malicious server tricks a client into processing malformed data. In the context of XMPP, which often handles sensitive real-time communications, compromising the integrity of the client software undermines trust in the entire messaging ecosystem. The reliance on base64 decoding of the salt attribute introduces an additional layer of complexity that must be carefully validated before memory allocation or copying operations occur.
Mitigation strategies for this vulnerability require both immediate patching and long-term architectural improvements. Organizations utilizing libstrophe should immediately upgrade to a version later than 0.14.0, where developers have implemented proper length checks and bounds validation within the SCRAM_Hi function. For systems that cannot be patched instantly, deploying network-level controls such as deep packet inspection firewalls can help identify and block XMPP traffic containing abnormally large salt attributes in server-first-messages. Additionally, enabling stack protection mechanisms like Stack Canaries or Address Space Layout Randomization during compilation can mitigate the risk of successful code execution by making it significantly harder for attackers to predict memory layouts and overwrite critical pointers. Developers should also enforce strict input validation on all data received from external sources, ensuring that decoded lengths are verified against buffer capacities before any copy operations take place. Regular security audits focusing on cryptographic implementation details in XMPP clients will help prevent similar flaws in future releases.