CVE-2026-49476CWE-400CWE-770

Soup Sieve: Memory Exhaustion via Large Comma-Separated Selector Lists in soupsieve

High · published July 14, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
50.2
In the wild
Unconfirmed
What it is

Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 2.8.4, the CSS selector parser in soupsieve allocates unbounded memory when compiling large comma-separated selector lists, allowing an attacker who can supply a crafted selector string to soupsieve.compile() or Beautiful Soup .select() / .select_one() to allocate hundreds of megabytes of heap memory from a relatively small input and cause denial of service. This issue is fixed in version 2.8.4.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00644 · 50.2th percentile
Weaknesses
CWE-400 · Uncontrolled Resource Consumption; CWE-770 · Allocation of Resources Without Limits or Throttling
Published
2026-07-14T20:53Z
EPSS history
Timeline
  • 14 JUL 20:53Z
    Soup Sieve: Memory Exhaustion via Large Comma-Separated Selector Lists in soupsieve
    cvelistv5