CVE-2026-49477
Description
A flaw was found in soupsieve, a CSS selector library. This vulnerability allows a remote attacker to cause a Denial of Service (DoS) by supplying specially crafted, untrusted CSS selector strings. The flaw occurs due to a regular expression vulnerable to catastrophic backtracking when processing an attribute selector with an unterminated quoted value, leading to CPU exhaustion.
Statement
Important: A regular expression denial of service (ReDoS) flaw in the soupsieve library can lead to CPU exhaustion. A remote attacker can exploit this by supplying a small, specially crafted CSS selector string to applications that process untrusted CSS, potentially blocking worker threads and causing a complete service denial in affected Red Hat products.
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 | 7.5 | N/A | 7.5 |
| 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 | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/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.
Frequently Asked Questions
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
