CVE-2026-19487
Description
A flaw was found in Perl. The regular expression engine may produce incorrect match results due to a stale failure flag in the Aho-Corasick prescan, which causes it to end prematurely. This can lead to the engine missing valid matches or matching on the wrong branch. As a result, applications that use regular expressions for critical functions like access control or data filtering could make erroneous decisions, potentially leading to security bypasses or unintended information disclosure.
Statement
Red Hat is aware of a flaw in Perl's regular expression engine where a stale failure flag in the Aho-Corasick prescan can cause the engine to terminate early, potentially missing valid matches or matching on the wrong alternation branch. Applications using Perl regular expressions for access control or filtering decisions may produce incorrect results. Red Hat products are affected and updates will be provided when available.
Mitigation
There is no mitigation available. Applications relying on Perl regular expressions for security-critical decisions (access control, input filtering) should implement defense-in-depth measures and monitor for updates.
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 | 6.5 | N/A | 5.3 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | None |
| Integrity Impact | Low | N/A | None |
| Availability Impact | None | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (Other); DoS: Resource Consumption (Memory); DoS: Resource Consumption (CPU)
An attacker that can influence the allocation of resources that are not properly released could deplete the available resource pool and prevent all other processes from accessing the same type of resource. Frequently-affected resources include memory, CPU, disk space, power or battery, etc.
Frequently Asked Questions
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