CVE-2014-0198 in OpenSSL
Summary
by MITRE
The do_ssl3_write function in s3_pkt.c in OpenSSL 1.x through 1.0.1g, when SSL_MODE_RELEASE_BUFFERS is enabled, does not properly manage a buffer pointer during certain recursive calls, which allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via vectors that trigger an alert condition.
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Analysis
by VulDB Data Team • 05/12/2026
The vulnerability identified as CVE-2014-0198 represents a critical buffer management flaw within the OpenSSL cryptographic library that affects versions 1.0.0 through 1.0.1g. This issue resides in the do_ssl3_write function located in the s3_pkt.c source file, where improper handling of buffer pointers during recursive function calls creates exploitable conditions. The vulnerability specifically manifests when the SSL_MODE_RELEASE_BUFFERS mode is enabled, a configuration that optimizes memory usage by releasing buffers after use but introduces dangerous pointer management issues. The flaw stems from the OpenSSL implementation's recursive call handling where buffer pointers are not correctly maintained across nested function invocations, leading to potential NULL pointer dereferences that can crash applications.
The technical exploitation of this vulnerability occurs through carefully crafted network traffic that triggers SSL alert conditions while the SSL_MODE_RELEASE_BUFFERS flag is active. When the recursive SSL3 write operations are executed, the buffer pointer management fails to preserve the correct memory references, causing the application to attempt to dereference a NULL pointer during the alert handling process. This specific implementation flaw falls under the CWE-476 category of NULL Pointer Dereference, which is classified as a common weakness in software security practices. The vulnerability demonstrates poor memory management practices in recursive function calls where state information is not properly preserved or restored across nested invocations, creating a predictable crash condition that can be reliably triggered by remote attackers.
From an operational impact perspective, this vulnerability poses significant risks to any system running OpenSSL with SSL_MODE_RELEASE_BUFFERS enabled, including web servers, email servers, and any network services that utilize SSL/TLS encryption. The denial of service condition can be easily triggered by sending malformed SSL packets that cause the application to crash and restart, potentially leading to service disruption and resource exhaustion. The ATT&CK framework categorizes this as a Denial of Service attack technique under the T1499.004 sub-technique for Network Denial of Service, where attackers exploit implementation flaws in network protocols to disrupt service availability. The vulnerability's remote exploitability means that attackers can trigger the condition without requiring local access, making it particularly dangerous for publicly exposed services.
The mitigation strategies for CVE-2014-0198 primarily involve updating to OpenSSL versions 1.0.1h or later, which contain the necessary fixes for proper buffer pointer management during recursive calls. Organizations should also consider disabling SSL_MODE_RELEASE_BUFFERS if the vulnerability cannot be immediately patched, as this configuration parameter directly enables the exploitable condition. Security teams should implement monitoring for unusual application crashes or restart patterns that might indicate exploitation attempts, particularly in SSL/TLS services. The vulnerability highlights the importance of proper state management in recursive functions and serves as a reminder of the critical need for thorough code review and testing of cryptographic libraries, especially when implementing memory optimization features that might introduce complex pointer management scenarios. Additionally, implementing network segmentation and access controls can help limit the potential impact of such exploits while patches are being deployed across the infrastructure.