CVE-2026-102473
Description
A flaw was found in dash. When built without libc fnmatch, the internal pmatch() matcher implements * by unbounded recursion over candidate positions. A local user who can plant filenames, or otherwise feed that matcher, can make a short multi-star pattern such as ....*.tar.gz consume excessive CPU.
Statement
Red Hat rates this vulnerability as having a Moderate impact because exploitation requires local access and can only result in a denial of service through excessive CPU resource consumption, without compromising system confidentiality or integrity. Furthermore, standard builds on Red Hat Enterprise Linux utilize glibc pattern matching facilities rather than the standalone fallback implementation, significantly limiting exposure under default configurations. Exploitation is constrained to non-standard environments where internal pattern expansion is active and untrusted users are permitted to provide wildcard expressions or crafted directory structures.
Mitigation
Rebuild dash with --enable-fnmatch so pathname matching uses libc fnmatch. Until then, do not run dash globs, case, or ${var#pat} / ${var%pat} against attacker-controlled names with multi-star patterns. There is no upstream backtracking bound in the internal matcher.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 5.5 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU)
Attackers can create crafted inputs that intentionally cause the regular expression to use excessive backtracking in a way that causes the CPU consumption to spike.
Acknowledgements
Red Hat would like to thank Shubham Raj (Causal Security) for reporting this issue.
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