A flaw was found in p11-kit. A remote attacker could exploit this vulnerability by calling the CDeriveKey function on a remote token with specific IBM kyber or IBM btc derive mechanism parameters set to NULL. This could lead to the RPC-client attempting to return an uninitialized value, potentially resulting in a NULL dereference or undefined behavior. This issue may cause an application level denial of service or other unpredictable system states.

A flaw was found in p11-kit. A local attacker, or one with equivalent access to a reachable RPC channel, could exploit an integer overflow vulnerability. By sending specially crafted messages, the attacker can cause the system to miscalculate memory allocation for nested attributes. This leads to a memory corruption issue, specifically a heap out-of-bounds write, which can crash the p11-kit RPC parsing process, resulting in a Denial of Service (DoS). This vulnerability is only exploitable on 32 bit systems.

A flaw was found in p11-kit. The RPC message attribute parsing functions p11rpcmessagegetattribute() and p11rpcmessagegetattributearrayvalue() in p11-kit/rpc-message.c form a mutually-recursive call chain with no depth limit when processing CKAWRAPTEMPLATE, CKAUNWRAPTEMPLATE, and CKADERIVETEMPLATE attribute types. Similarly, protoreadattributebufferarray() in p11-kit/rpc-server.c recurses without bound for ISATTRIBUTEARRAY types.

An attacker who can connect to the p11-kit RPC server via Unix domain socket (/run/user/<uid>/p11-kit/pkcs11-) can send a specially crafted CCreateObject request with deeply nested template attributes (~50,000 levels, ~650KB wire data), causing stack exhaustion and a SIGSEGV/SIGBUS crash of the p11-kit process. No authentication is required beyond same-user access to the Unix domain socket.

This results in denial of service for the p11-kit server and any dependent processes such as SSH agents, VPN clients, or web browsers using p11-kit for PKCS#11 module management. The recursive attribute support was introduced in commit 6529b540 (Feb 2024) without a depth bound.

Summary: potential NULL dereference in p11-kit when calling CDeriveKey remotely with specific parameters.

Requirements to exploit: if an attacker calls CDeriveKey on a remote token with either mechanism IBM kyber or IBM btc derive, with specific mechanism parameter values set to NULL. The RPC-client might attempt to return an uninitialized value potentially resulting in a NULL dereference or undefined behavior.

A slight overhaul of p11rpcbuffergetibmkybermechparamupdate and p11rpcbuffergetibmbtcderivemechparamupdate functions where variable data could potentially be used uninitialized.

Report from static analysis:

1. Defect type: UNINIT 1. p11-kit-0.26.1/p11-kit/rpc-message.c:1706:2: vardecl: Declaring variable "data" without initializer. 11. p11-kit-0.26.1/p11-kit/rpc-message.c:1732:5: uninituseincall: Using uninitialized value "data" when calling "memcpy". [Note: The source code implementation of the function has been overridden by a builtin model.] 1730| 1731| if (params->pCipher && params->ulCipherLen == len) { 1732|-> memcpy(params->pCipher, data, len); 1733| params->ulCipherLen = len; 1734| } else { 2. Defect type: UNINIT 1. p11-kit-0.26.1/p11-kit/rpc-message.c:1706:2: vardecl: Declaring variable "data" without initializer. 11. p11-kit-0.26.1/p11-kit/rpc-message.c:1735:5: uninituse: Using uninitialized value "data". 1733| params->ulCipherLen = len; 1734| } else { 1735|-> params->pCipher = (void ) data; 1736| params->ulCipherLen = len; 1737| } 3. Defect type: UNINIT 1. p11-kit-0.26.1/p11-kit/rpc-message.c:1776:2: vardecl: Declaring variable "data" without initializer. 9. p11-kit-0.26.1/p11-kit/rpc-message.c:1797:4: uninituseincall: Using uninitialized value "data" when calling "memcpy". [Note: The source code implementation of the function has been overridden by a builtin model.] 1795| 1796| if (params->pChainCode && params->ulChainCodeLen == len) { 1797|-> memcpy(params->pChainCode, data, len); 1798| params->ulChainCodeLen = len; 1799| } else { 4. Defect type: UNINIT 1. p11-kit-0.26.1/p11-kit/rpc-message.c:1776:2: vardecl: Declaring variable "data" without initializer. 9. p11-kit-0.26.1/p11-kit/rpc-message.c:1800:4: uninituse: Using uninitialized value "data". 1798| params->ulChainCodeLen = len; 1799| } else { 1800|-> params->pChainCode = (void ) data; 1801| params->ulChainCodeLen = len; 1802| }