CVE-2026-3961 Overview
A Server-Side Request Forgery (SSRF) vulnerability has been identified in zyddnys manga-image-translator up to version beta-0.3. The vulnerability exists in the to_pil_image function within the file manga-image-translator-main/server/request_extraction.py, which is part of the Translate Endpoints component. This flaw allows remote attackers to manipulate the server into making unauthorized requests to internal or external resources, potentially exposing sensitive internal services or bypassing network security controls.
Critical Impact
Remote attackers can exploit this SSRF vulnerability to access internal network resources, potentially leading to data exfiltration, internal service enumeration, or further exploitation of backend systems. The exploit has been publicly disclosed and the vendor has not yet responded to the issue report.
Affected Products
- zyddnys manga-image-translator up to beta-0.3
- manga-image-translator Translate Endpoints component
- request_extraction.py module containing to_pil_image function
Discovery Timeline
- 2026-03-11 - CVE-2026-3961 published to NVD
- 2026-03-12 - Last updated in NVD database
Technical Details for CVE-2026-3961
Vulnerability Analysis
This vulnerability is classified as CWE-918 (Server-Side Request Forgery). The affected to_pil_image function in the request_extraction.py file fails to properly validate user-supplied input before making server-side requests. When processing image translation requests through the Translate Endpoints, the application accepts URLs or resource identifiers that are then fetched by the server without adequate validation or sanitization.
SSRF vulnerabilities of this nature allow attackers to abuse the server's network position to access resources that would otherwise be inaccessible. This can include internal services, cloud metadata endpoints, or other protected network resources. The vulnerability can be exploited remotely by authenticated users with low privileges, requiring no user interaction.
Root Cause
The root cause of this vulnerability lies in insufficient input validation within the to_pil_image function. The function appears to accept image source parameters that can be manipulated to point to arbitrary URLs or internal network addresses. Without proper URL validation, allowlisting, or blocking of internal IP ranges, the server will fetch resources from attacker-controlled destinations or internal network locations.
Attack Vector
The attack vector is network-based, allowing remote exploitation. An attacker with low-level privileges can craft malicious requests to the Translate Endpoints, supplying URLs that point to internal services (such as http://localhost/, http://127.0.0.1/, or cloud metadata services like http://169.254.169.254/). The server then processes these requests, effectively acting as a proxy for the attacker.
The vulnerability can be exploited to:
- Enumerate internal network services and ports
- Access cloud instance metadata containing sensitive credentials
- Bypass firewall restrictions by using the server as an intermediary
- Potentially chain with other vulnerabilities for more severe attacks
For technical details on the vulnerability mechanism, refer to GitHub Issue #1118 and GitHub Issue #1119 which contain the public disclosure information.
Detection Methods for CVE-2026-3961
Indicators of Compromise
- Unusual outbound requests from the manga-image-translator server to internal IP addresses (127.0.0.1, 10.x.x.x, 172.16.x.x, 192.168.x.x)
- Server requests to cloud metadata endpoints such as 169.254.169.254
- Translation endpoint requests containing URL parameters pointing to non-standard or internal resources
- Unexpected network connections from the application server to internal services
Detection Strategies
- Monitor network traffic from the manga-image-translator server for connections to internal IP ranges or localhost
- Implement web application firewall (WAF) rules to detect and block SSRF patterns in request parameters
- Review application logs for translation requests containing suspicious URL schemes (file://, gopher://, dict://) or internal addresses
- Deploy endpoint detection solutions to identify abnormal outbound connection patterns from the server
Monitoring Recommendations
- Enable detailed logging for all requests to the Translate Endpoints, including the full request payload
- Set up alerts for any outbound connections from the application server to RFC 1918 private address ranges
- Monitor for connection attempts to common cloud metadata IP addresses from web-facing servers
- Implement network segmentation and monitor east-west traffic for anomalous patterns
How to Mitigate CVE-2026-3961
Immediate Actions Required
- Restrict access to the manga-image-translator Translate Endpoints to trusted users only
- Implement network-level controls to prevent the server from accessing internal resources
- Consider disabling the affected translation functionality until a patch is available
- Review and audit all recent requests to the translation endpoints for potential exploitation
Patch Information
As of the last update, the project maintainers have not responded to the vulnerability report. No official patch is currently available. Organizations using manga-image-translator should monitor the GitHub repository for security updates and consider the workarounds below until an official fix is released.
Workarounds
- Implement an allowlist of permitted domains for image fetching in a reverse proxy or WAF
- Deploy network segmentation to isolate the manga-image-translator server from sensitive internal resources
- Use a forward proxy that blocks requests to internal IP ranges for all outbound server requests
- Modify the to_pil_image function in request_extraction.py to validate and sanitize URL inputs before processing
# Example: Block internal IP ranges using iptables on the server
# Prevent SSRF access to internal networks
iptables -A OUTPUT -d 127.0.0.0/8 -p tcp -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -d 10.0.0.0/8 -p tcp -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -p tcp -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -p tcp -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -d 169.254.169.254/32 -p tcp -m owner --uid-owner www-data -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
