CVE-2015-2313 in Cap'n Proto
Summary
by MITRE
Sandstorm Cap'n Proto before 0.4.1.1 and 0.5.x before 0.5.1.2, when an application invokes the totalSize method on an object reader, allows remote peers to cause a denial of service (CPU consumption) via a crafted small message, which triggers a "tight" for loop. NOTE: this vulnerability exists because of an incomplete fix for CVE-2015-2312.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 12/15/2022
The vulnerability described in CVE-2015-2313 represents a denial of service flaw within the Sandstorm Cap'n Proto library, a high-performance serialization framework designed for efficient data exchange in distributed systems. This issue affects versions prior to 0.4.1.1 and 0.5.x prior to 0.5.1.2, demonstrating the persistent nature of security flaws that can linger despite previous patches. The vulnerability specifically targets the totalSize method functionality within object readers, creating a scenario where remote adversaries can manipulate system resources through carefully crafted input data. The underlying mechanism involves a tight loop execution that consumes excessive cpu cycles, effectively allowing attackers to perform resource exhaustion attacks against systems utilizing this library.
The technical implementation of this vulnerability stems from an incomplete remediation of a previous security issue, CVE-2015-2312, which highlights the complexity of security patching in software libraries. When an application processes a crafted small message through the totalSize method, the object reader enters an infinite or extremely tight loop that rapidly consumes cpu resources without proper bounds checking or loop termination conditions. This flaw operates at the protocol level where malformed data can trigger unexpected behavior in the parsing logic, specifically targeting the memory management and size calculation routines. The tight loop condition occurs because the library fails to validate message structures properly, allowing attackers to craft inputs that cause the internal iteration logic to continue indefinitely until system resources are exhausted.
From an operational impact perspective, this vulnerability poses significant risks to systems that rely on Sandstorm Cap'n Proto for communication between distributed components, particularly in high-throughput environments where resource consumption directly translates to service availability. The denial of service condition can be triggered remotely without authentication requirements, making it particularly dangerous for network-facing applications. Systems utilizing this library may experience complete service unavailability as cpu resources are consumed by the malicious loop, potentially affecting multiple concurrent connections or processes depending on the application architecture. The vulnerability's impact extends beyond simple resource exhaustion to potentially compromise the entire application stack when combined with other attack vectors or when systems operate under resource constraints.
The remediation approach for this vulnerability requires updating to the patched versions 0.4.1.1 and 0.5.1.2, which contain proper bounds checking and loop termination logic to prevent the tight loop execution. Security practitioners should implement comprehensive testing procedures to verify that all applications using Sandstorm Cap'n Proto have been updated and that no legacy versions remain in production. Additionally, monitoring systems should be configured to detect unusual cpu consumption patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-835, which addresses infinite loops or tight loops in software implementations, and maps to ATT&CK technique T1499.004 for network denial of service attacks. Organizations should also consider implementing input validation measures and rate limiting for protocol parsing operations as additional defensive controls to mitigate the risk of similar vulnerabilities in other components of their distributed systems architecture.