CVE-2026-70493

ReDoS vulnerability in Open WebUI knowledge search causes Denial of Service.

• CVSS 6.5
• 1333
• Resource Management
• Remote

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.6 until 0.11.0, the built-in knowledge search path in backend/open_webui/tools/knowledge_fs.py and backend/open_webui/tools/builtin.py let a chat participant choose a pattern used to grep knowledge files. Patterns containing regex metacharacters were compiled with Python's backtracking re engine and run against every line of every reachable file with no time limit, so a crafted pattern such as (x|x)*y and one matching uploaded file line can pin one CPU core and block the event loop. This causes availability impact for every other user of the affected worker. This issue is fixed in 0.11.0.

CVE

CVE-2026-70493

CWE

1333

CVSS base score

6.5

Published

2026-08-04

OWASP

A04 Insecure Design

Orthogonal defect classification

Algorithm

Code defect classification

Missing Check

Category

Resource Management

Subcategory

Resource Exhaustion

Accessibility scope

Remote

Impact

Denial of Service (DoS)

Affected component

Open WebUI

Fixed by upgrading

Yes

Solution

Upgrade to Open WebUI version 0.11.0.

import re
import os
from typing import List


def knowledge_search(query: str, file_paths: List[str]) -> List[str]:
    """Grep knowledge files for a chat-provided pattern."""
    matches = []
    for file_path in file_paths:
        try:
            with open(file_path, "r", encoding="utf-8") as f:
                for line in f:
                    # VULNERABLE: user-controlled regex compiled with backtracking engine, no limit (ReDoS)
                    if re.search(query, line, re.IGNORECASE):
                        matches.append(
                            f"Found in {os.path.basename(file_path)}: {line.strip()}"
                        )
        except Exception:
            pass
    return matches

import re
import os
from typing import List


def knowledge_search(query: str, file_paths: List[str]) -> List[str]:
    """Grep knowledge files for a chat-provided pattern."""
    # FIX: escape metacharacters so the pattern is matched literally, no backtracking
    pattern = re.compile(re.escape(query), re.IGNORECASE)
    matches = []
    for file_path in file_paths:
        try:
            with open(file_path, "r", encoding="utf-8") as f:
                for line in f:
                    if pattern.search(line):
                        matches.append(
                            f"Found in {os.path.basename(file_path)}: {line.strip()}"
                        )
        except Exception:
            pass
    return matches

(x|x)*y

@misc{vaitp:cve202670493,
  title        = {{ReDoS vulnerability in Open WebUI knowledge search causes Denial of Service.}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2026},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2026-70493},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2026-70493/}}
}