CWEweakness

CWE-1281 Sequence of Processor Instructions Leads to Unexpected Behavior

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Abstraction
Base
Structure
Simple
Status
Incomplete
Languages
Not Language-Specific
CWE version
5.0

Description

Specific combinations of processor instructions lead to undesirable behavior such as locking the processor until a hard reset performed.

Extended description

If the instruction set architecture (ISA) and processor logic are not designed carefully and tested thoroughly, certain combinations of instructions may lead to locking the processor or other unexpected and undesirable behavior. Upon encountering unimplemented instruction opcodes or illegal instruction operands, the processor should throw an exception and carry on without negatively impacting security. However, specific combinations of legal and illegal instructions may cause unexpected behavior with security implications such as allowing unprivileged programs to completely lock the CPU.

Common consequences

• Integrity, Availability: Varies by Context

Potential mitigations

• [Testing] Implement a rigorous testing strategy that incorporates randomization to explore instruction sequences that are unlikely to appear in normal workloads in order to identify halt and catch fire instruction sequences. • [Patching and Maintenance] Patch operating system to avoid running Halt and Catch Fire type sequences or to mitigate the damage caused by unexpected behavior. See [REF-1108].

Observed examples

• CVE-2021-26339: A bug in AMD CPU's core logic allows a potential DoS by using a specific x86 instruction sequence to hang the processor • CVE-1999-1476: A bug in some Intel Pentium processors allow DoS (hang) via an invalid "CMPXCHG8B" instruction, causing a deadlock

Related

Attack pattern · CAPEC (1)

  • CAPEC-212 Functionality Misuse attack pattern

Observed example · CVE (2)

  • CVE-2021-26339 A bug in AMD CPU’s core logic may allow for an attacker, using specific code from an unprivileged VM, to trigger a CPU core hang resulting… vulnerability
  • CVE-1999-1476 A bug in Intel Pentium processor (MMX and Overdrive) allows local users to cause a denial of service (hang) in Intel-based operating… vulnerability

Child of · CWE (1)

  • CWE-691 Insufficient Control Flow Management weakness

Referenced by CAPEC · weakness (1)

  • CAPEC-212 Functionality Misuse attack pattern

Referenced by CVE · weakness (7)

  • CVE-2025-51679 An issue was discovered in openRISC OR1200 commit 83ac6b. vulnerability
  • CVE-2026-47233 Admidio is an open-source user management solution. vulnerability
  • CVE-2025-56301 An issue was discovered in Chipsalliance Rocket-Chip commit f517abbf41abb65cea37421d3559f9739efd00a9 (2025-01-29) allowing attackers to… vulnerability
  • CVE-2025-22840 Sequence of processor instructions leads to unexpected behavior for some Intel(R) Xeon(R) 6 Scalable processors may allow an authenticated… vulnerability
  • CVE-2024-37020 Sequence of processor instructions leads to unexpected behavior in the Intel(R) DSA V1.0 for some Intel(R) Xeon(R) Processors may allow an… vulnerability
  • CVE-2023-46103 Sequence of processor instructions leads to unexpected behavior in Intel(R) Core(TM) Ultra Processors may allow an authenticated user to… vulnerability
  • CVE-2023-23583 Sequence of processor instructions leads to unexpected behavior for some Intel(R) Processors may allow an authenticated user to potentially… vulnerability