CVE-2026-49476
Description
A flaw was found in soupsieve, a CSS selector library used with Beautiful Soup 4. This vulnerability allows a remote attacker to cause a denial of service (DoS) by supplying a specially crafted CSS selector string. The parser allocates unbounded memory when compiling large, comma-separated selector lists, leading to excessive memory consumption and system instability.
Statement
An uncontrolled resource consumption vulnerability was found in the soupsieve Python package, a CSS selector library used by BeautifulSoup4. A remote attacker could provide a crafted CSS selector string that causes excessive memory or CPU consumption, leading to a denial of service condition.
It requires the application to accept untrusted CSS selectors supplied in one of the following sinks:
- soupsieve.compile()
- BeautifulSoup.select()
- BeautifulSoup.select_one()
This is an uncommon scenario.
Mitigation
There is no mitigation for this flaw other than updating the soupsieve package when upstream patches are available. The impact is limited to availability (denial of service) — an attacker cannot access or modify data through this vulnerability. Applications that do not process untrusted CSS selector strings are at reduced risk.
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 | 5.9 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | 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:H/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); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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