CAPEC-46
Overflow Variables and Tags
This type of attack leverages the use of tags or variables from a formatted configuration data to cause buffer overflow. The adversary crafts a malicious HTML page or configuration file that includes oversized strings, thus causing an overflow.
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Explain the attack pattern CAPEC-46: Overflow Variables and Tags: how it unfolds, what it needs and how to prevent and detect it in my systems. Use https://capec.mitre.org/data/definitions/46.html and https://cve.bz/cve/capec/46?via=ask-ai-copy, which lists recent CVEs with the weaknesses it exploits. Cite the sources.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this attack pattern's id and public links.
How the attack unfolds
Explore
The attacker looks for a way in.
[Identify target application] The adversary identifies a target application or program to perform the buffer overflow on. Adversaries look for applications or programs that accept formatted files, such as configuration files, as input.
Experiment
They probe what they found.
[Find injection vector] The adversary identifies an injection vector to deliver the excessive content to the targeted application's buffer.
1 technique
- Knowing the type of file that an application takes as input, the adversary takes a normal input file and modifies a single variable or tag to contain a large amount of data. If there is a crash, this means that a buffer overflow attack is possible. The adversary will keep changing single variables or tags one by one until they see a change in behavior.
[Craft overflow content] The adversary crafts the content to be injected. If the intent is to simply cause the software to crash, the content need only consist of an excessive quantity of random data. If the intent is to leverage the overflow for execution of arbitrary code, the adversary crafts the payload in such a way that the overwritten return address is replaced with one of the adversary's choosing.
2 techniques
- Create malicious shellcode that will execute when the program execution is returned to it.
- Use a NOP-sled in the overflow content to more easily "slide" into the malicious code. This is done so that the exact return address need not be correct, only in the range of all of the NOPs
Exploit
They carry out the attack.
[Overflow the buffer] The adversary will upload the crafted file to the application, causing a buffer overflow.
Prerequisites
The target program consumes user-controllable data in the form of tags or variables.
The target program does not perform sufficient boundary checking.
Skills required
- Low skill
An adversary can simply overflow a buffer by inserting a long string into an adversary-modifiable injection vector. The result can be a DoS.
- High skill
Exploiting a buffer overflow to inject malicious code into the stack of a software system or even the heap can require a higher skill level.
Consequences
| Impact | Affects | Note |
|---|---|---|
| Unreliable Execution | Availability | |
| Execute Unauthorized Commands | Confidentiality, Integrity, Availability | Run Arbitrary Code |
| Read Data | Confidentiality | |
| Modify Data | Integrity |
Mitigations
Use a language or compiler that performs automatic bounds checking.
Use an abstraction library to abstract away risky APIs. Not a complete solution.
Compiler-based canary mechanisms such as StackGuard, ProPolice and the Microsoft Visual Studio /GS flag. Unless this provides automatic bounds checking, it is not a complete solution.
Use OS-level preventative functionality. Not a complete solution.
Do not trust input data from user. Validate all user input.
Weaknesses it exploits
- CWE-20 Improper Input Validation
- CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component
- CWE-118 Incorrect Access of Indexable Resource
- CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer
- CWE-120 Buffer Copy without Checking Size of Input
- CWE-680 Integer Overflow to Buffer Overflow
- CWE-697 Incorrect Comparison
- CWE-733 Compiler Optimization Removal or Modification of Security-critical Code
Recent CVEs with these weaknesses
- 9.6CVE-2026-108186
Improper Input Validation in Zoom Workplace for Windows may allow an unauthenticated user to conduct an escalation of privilege via network access.
- 4.9CVE-2026-105427
Improper input validation in Ivanti EPMM before version 12.10.0.1, 12.9.0.3, and 12.8.0.5 allows a remote authenticated attacker with admin privileges to permanently disable all Apache HTTPS services resulting in denial of service.
- 6.7CVE-2026-105426
Improper input validation in Ivanti EPMM before version 12.10.0.1, 12.9.0.3, and 12.8.0.5 allows a remote authenticated attacker with admin privileges to set arbitrary Linux kernel parameters as root.
- 4.3CVE-2026-123178
An insufficient input validation vulnerability in the listed NETGEAR Orbi Models router allows an authenticated administrator connected to the local network to execute unauthorized commands and modify the router’s software and functionalit…
- 8.8CVE-2026-124948
Incorrect boundary conditions, use-after-free in the Graphics component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.
- 8.8CVE-2026-124947
Incorrect boundary conditions in the Graphics component. This vulnerability was fixed in Firefox 160.
- 8.8CVE-2026-124926
Incorrect boundary conditions in the WebRTC component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.
- 8.8CVE-2026-124924
Incorrect boundary conditions in the Graphics: WebRender component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.
The newest records naming one of them. Each weakness's page lists them all.
Related attack patterns
- Part of
- CAPEC-100 Overflow Buffers
Examples
A buffer overflow vulnerability exists in the Yamaha MidiPlug that can be accessed via a Text variable found …
A buffer overflow vulnerability exists in the Yamaha MidiPlug that can be accessed via a Text variable found in an EMBED tag.
See also: CVE-1999-0946
A buffer overflow in Exim allows local users to gain root privileges by providing a long :include: option in …
A buffer overflow in Exim allows local users to gain root privileges by providing a long :include: option in a .forward file.
See also: CVE-1999-0971
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