Horizon Alert
Summary of the vulnerability and why it matters
A specific input format in the GNU C Library can lead to a small memory overflow, potentially allowing for code execution. This is concerning because this library is foundational to many applications and systems.
- Affects widely used systems.
- Can lead to significant compromise.
- Can be triggered remotely.
Attack Path
How an attacker could exploit the issue
An attacker could exploit this flaw by crafting malicious input to a program using a vulnerable version of glibc. By providing a specific format string to `scanf` with a large width specifier, they could trigger a one-byte heap overflow. This overflow could then be leveraged to corrupt heap metadata, potentially leading to arbitrary code execution.
- Affects programs using `scanf` with `%mc`.
- Requires specific format string and explicit width.
- Heap overflow corrupts memory for code execution.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability, a heap buffer overflow in the GNU C Library's `scanf` family of functions, presents an attractive target for attackers due to its remote unauthenticated exploitability and critical impact. While the specific function usage is required, its presence in a fundamental library means widespread potential for exploitation across many applications. Attackers are likely to investigate and develop exploits for this flaw.
- Exploitable remotely without authentication.
- Exploits may be developed.
- Vulnerability in a core library.
Priority actions
Operational Fix
Recommended remediation, mitigation, and detection steps
Prioritize identifying and isolating systems running GNU C Library versions 2.7 through 2.43 that process user-supplied input via `scanf` family functions with a `%mc` format specifier and an explicit width greater than 1024. This vulnerability allows for a heap buffer overflow and could lead to code execution.
- Block or strictly validate all input to affected `scanf` calls.
- Isolate or take offline services using vulnerable Glibc.
- Update Glibc to a non-vulnerable version.
