CWE-1257 Base Incomplete

Improper Access Control Applied to Mirrored or Aliased Memory Regions

This vulnerability occurs when a hardware design maps the same physical memory to multiple addresses (aliasing or mirroring) but fails to apply consistent read/write permissions across all these…

Definition

What is CWE-1257?

This vulnerability occurs when a hardware design maps the same physical memory to multiple addresses (aliasing or mirroring) but fails to apply consistent read/write permissions across all these addresses. An attacker blocked from accessing a protected memory region might still reach the same data through its unprotected aliased address, bypassing security controls.
Hardware designs often use memory aliasing for legitimate purposes like redundancy, fault tolerance, or simplifying address decoding logic. However, a critical security flaw emerges when the access control logic checks permissions for only one address path and not its aliases. This creates an inconsistent security state where the same physical memory cell has different protection levels depending on which logical address is used to access it. From a developer or attacker perspective, this inconsistency becomes an exploitable bypass. An untrusted process or agent denied access to a primary address can simply target the alternate, aliased address to read or write protected memory. Furthermore, if an attacker can manipulate system address mapping registers, they might be able to create malicious aliases themselves, fundamentally undermining the hardware's memory isolation guarantees.
Real-world impact

Real-world CVEs caused by CWE-1257

No public CVE references are linked to this CWE in MITRE's catalog yet.

How attackers exploit it

Step-by-step attacker path

  1. 1

    Identify a code path that handles untrusted input without validation.

  2. 2

    Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.

  3. 3

    Deliver the payload through a normal request and observe the application's reaction.

  4. 4

    Iterate until the response leaks data, executes attacker code, or escalates privileges.

Vulnerable code example

Vulnerable Other

In a System-on-a-Chip (SoC) design the system fabric uses 16 bit addresses. An IP unit (Unit_A) has 4 kilobyte of internal memory which is mapped into a 16 kilobyte address range in the system fabric address map. | | | | System Address | Mapped to | | 0x0000 - 0x3FFF | Unit_A registers : 0x0000 - 0x0FFF | | 0x4000 - 0xFFFF | Other IPs & Memory | To protect the register controls in Unit_A unprivileged software is blocked from accessing addresses between 0x0000 - 0x0FFF. The address decoder of Unit_A masks off the higher order address bits and decodes only the lower 12 bits for computing the offset into the 4 kilobyte internal memory space.

Vulnerable Other 
In this design the aliased memory address ranges are these:



0x0000 - 0x0FFF


0x1000 - 0x1FFF


0x2000 - 0x2FFF


0x3000 - 0x3FFF


 The same register can be accessed using four different addresses: 0x0000, 0x1000, 0x2000, 0x3000. 


 The system address filter only blocks access to range 0x0000 - 0x0FFF and does not block access to the aliased addresses in 0x1000 - 0x3FFF range. Thus, untrusted software can leverage the aliased memory addresses to bypass the memory protection.
Secure code example

Secure Other

Secure Other 
In this design the aliased memory addresses (0x1000 - 0x3FFF) could be blocked from all system software access since they are not used by software. 


 Alternately, the MPU logic can be changed to apply the memory protection policies to the full address range mapped to Unit_A (0x0000 - 0x3FFF).
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist

How to prevent CWE-1257

  • Architecture and Design / Implementation The checks should be applied for consistency access rights between primary memory regions and any mirrored or aliased memory regions. If different memory protection units (MPU) are protecting the aliased regions, their protected range definitions and policies should be synchronized.
  • Architecture and Design / Implementation The controls that allow enabling memory aliases or changing the size of mapped memory regions should only be programmable by trusted software components.
Detection signals

How to detect CWE-1257

SAST High

Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.

DAST Moderate

Run dynamic application security testing against the live endpoint.

Runtime Moderate

Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.

Code review Moderate

Code review: flag any new code that handles input from this surface without using the validated framework helpers.

Plexicus auto-fix

Plexicus auto-detects CWE-1257 and opens a fix PR in under 60 seconds.

Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.

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Frequently asked questions

Frequently asked questions

What is CWE-1257?

This vulnerability occurs when a hardware design maps the same physical memory to multiple addresses (aliasing or mirroring) but fails to apply consistent read/write permissions across all these addresses. An attacker blocked from accessing a protected memory region might still reach the same data through its unprotected aliased address, bypassing security controls.

How serious is CWE-1257?

MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.

What languages or platforms are affected by CWE-1257?

MITRE lists the following affected platforms: Not OS-Specific, Not Architecture-Specific, Memory Hardware, Processor Hardware, Microcontroller Hardware, Network on Chip Hardware, System on Chip.

How can I prevent CWE-1257?

The checks should be applied for consistency access rights between primary memory regions and any mirrored or aliased memory regions. If different memory protection units (MPU) are protecting the aliased regions, their protected range definitions and policies should be synchronized. The controls that allow enabling memory aliases or changing the size of mapped memory regions should only be programmable by trusted software components.

How does Plexicus detect and fix CWE-1257?

Plexicus's SAST engine matches the data-flow signature for CWE-1257 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.

Where can I learn more about CWE-1257?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/1257.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-1257

CWE-284 Parent

Improper Access Control

The software fails to properly limit who can access a resource, allowing unauthorized users or systems to interact with it.

CWE-1191 Sibling

On-Chip Debug and Test Interface With Improper Access Control

This vulnerability occurs when a hardware chip's debug or test interface (like JTAG) lacks proper access controls. Without correct…

CWE-1220 Sibling

Insufficient Granularity of Access Control

This vulnerability occurs when a system's access controls are too broad, allowing unauthorized users or processes to read or modify…

CWE-1224 Sibling

Improper Restriction of Write-Once Bit Fields

This vulnerability occurs when hardware write-once protection mechanisms, often called 'sticky bits,' are incorrectly implemented,…

CWE-1231 Sibling

Improper Prevention of Lock Bit Modification

This vulnerability occurs when hardware or firmware uses a lock bit to protect critical system registers or memory regions, but fails to…

CWE-1233 Sibling

Security-Sensitive Hardware Controls with Missing Lock Bit Protection

This vulnerability occurs when a hardware device uses a lock bit to protect critical configuration registers, but the lock fails to…

CWE-1252 Sibling

CPU Hardware Not Configured to Support Exclusivity of Write and Execute Operations

This vulnerability occurs when a CPU's hardware is not set up to enforce a strict separation between writing data to memory and executing…

CWE-1259 Sibling

Improper Restriction of Security Token Assignment

This vulnerability occurs when a System-on-a-Chip (SoC) fails to properly secure its Security Token mechanism. These tokens control which…

CWE-1260 Sibling

Improper Handling of Overlap Between Protected Memory Ranges

This vulnerability occurs when a system incorrectly allows different memory protection ranges to overlap. This flaw can let attackers…

Resources

Further reading

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