CVE-2026-1005 in wolfSSL
Summary
by MITRE • 03/19/2026
Integer underflow in wolfSSL packet sniffer <= 5.8.4 allows an attacker to cause a buffer overflow in the AEAD decryption path by injecting a TLS record shorter than the explicit IV plus authentication tag into traffic inspected by ssl_DecodePacket. The underflow wraps a 16-bit length to a large value that is passed to AEAD decryption routines, causing heap buffer overflow and a crash. An unauthenticated attacker can trigger this remotely via malformed TLS Application Data records.
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Analysis
by VulDB Data Team • 05/05/2026
The vulnerability identified as CVE-2026-1005 represents a critical integer underflow flaw within wolfSSL packet sniffer functionality affecting versions 5.8.4 and earlier. This vulnerability resides in the ssl_DecodePacket function which processes TLS records during network traffic inspection. The flaw manifests when processing TLS Application Data records that are shorter than the expected explicit IV plus authentication tag length, creating a scenario where a 16-bit length value undergoes underflow arithmetic. This mathematical error results in a large unsigned value that subsequently propagates to AEAD decryption routines, establishing a direct pathway for heap-based buffer overflow conditions. The integer underflow specifically maps to CWE-191 Integer Underflow or Wraparound, which is classified as a fundamental arithmetic error that can lead to unpredictable behavior and memory corruption.
The operational impact of this vulnerability extends beyond simple crash conditions to potentially enable more sophisticated attack vectors. When an attacker injects malformed TLS records that trigger the underflow condition, the resulting buffer overflow can cause application crashes or potentially allow arbitrary code execution depending on memory layout and exploitation circumstances. The vulnerability is particularly concerning because it operates at the TLS packet decoding layer where network traffic is processed, making it accessible to unauthenticated remote attackers who can manipulate TLS Application Data records. This represents a significant threat to systems relying on wolfSSL for secure communications, as the attack can be executed without requiring authentication credentials or privileged access to the target system.
The attack surface for this vulnerability encompasses any system utilizing wolfSSL packet sniffer functionality in versions up to and including 5.8.4, particularly those monitoring TLS traffic for security inspection or network analysis purposes. The specific conditions required for exploitation involve crafting malicious TLS records that are shorter than the expected length parameters, which can be accomplished through network-level manipulation or by compromising intermediate network devices that process TLS traffic. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving protocol manipulation and memory corruption, potentially enabling adversaries to achieve code execution or denial of service conditions. The vulnerability's classification as a remote attack vector means that network-based exploitation is possible without requiring physical access or local system privileges, making it particularly dangerous in networked environments where TLS traffic inspection is common.
Mitigation strategies for CVE-2026-1005 primarily focus on immediate version upgrades to wolfSSL 5.8.5 or later, which contain the necessary patches to prevent the integer underflow condition. Organizations should also implement network segmentation and monitoring to detect anomalous TLS traffic patterns that might indicate exploitation attempts. Additional protective measures include configuring firewalls to filter malformed TLS records and implementing intrusion detection systems that can identify potential exploitation signatures. The vulnerability demonstrates the importance of proper input validation and arithmetic boundary checking in cryptographic libraries, particularly those handling network protocol parsing. Security teams should conduct comprehensive vulnerability assessments to identify all systems using affected wolfSSL versions and prioritize remediation efforts based on risk exposure and network criticality. Regular security updates and patch management processes become essential to prevent similar vulnerabilities from being exploited in the future, as this flaw highlights the need for robust error handling in cryptographic protocol implementations.