CVE-2026-19499
Description
A flaw was found in glibc. The strfmon and strfmon_l functions are vulnerable to a buffer overflow when processing right-justified width padding. This occurs because an incorrect length is used for an internal memory operation, causing data to be written beyond its intended buffer. An attacker could exploit this by providing specially crafted input, potentially leading to arbitrary code execution or other severe impacts.
Statement
This Moderate impact buffer overflow in strfmon or strfmon_l within glibc occurs when an application uses right-justified width padding with a specific buffer size, leading to an out-of-bounds write. Exploitation requires a vulnerable application code path that processes attacker-controlled formatting input or uses a fixed susceptible formatting pattern, limiting its general exploitability in typical Red Hat deployments.
Mitigation
This issue is reachable only through applications that call glibc strfmon or strfmon_l with right-justified width padding into an undersized destination buffer. Prefer avoiding those APIs, or ensure destination buffers are sized for the full formatted result including padding. Where monetary formatting is exposed to untrusted input, restrict access to trusted clients.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.8 | N/A | 7.7 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | Low | N/A | High |
| Privileges Required | Low | N/A | None |
| User Interaction | Required | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | High |
| Integrity Impact | High | N/A | Low |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.
Integrity,Confidentiality,Availability,Access Control
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Modify Memory
Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. Besides important user data, heap-based overflows can be used to overwrite function pointers that may be living in memory, pointing it to the attacker's code. Even in applications that do not explicitly use function pointers, the run-time will usually leave many in memory. For example, object methods in C++ are generally implemented using function pointers. Even in C programs, there is often a global offset table used by the underlying runtime.
Integrity,Confidentiality,Availability,Access Control,Other
Technical Impact: Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Other
When the consequence is arbitrary code execution, this can often be used to subvert any other security service.
Acknowledgements
This issue was discovered by Found by AISLE in partnership with Red Hat (Aisle Research).
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