CVE-2026-26013
Description
A flaw was found in LangChain. The ChatOpenAI.get_num_tokens_from_messages method fetches arbitrary image_url values without validation when computing token counts for vision-enabled models. This issue allows an attacker to cause Server-Side Request Forgery (SSRF) by providing malicious image URLs in user input.
Statement
To exploit this issue, an attacker needs to be able to provide a malicious image_url to a LangChain instance. However, the server responses are not returned to the attacker (blind SSRF), increasing the complexity of exploitation. Additionally, an attacker can cause the server to fetch large files, potentially resulting in a high consumption of bandwidth or CPU, causing a limited impact to availability but not a complete denial of service. Due to these reasons, this vulnerability has been rated with a low impact.
Mitigation
To mitigate this issue, manually validate that all image_url fields use the HTTP/HTTPS protocols, point to allowed public domains and do not resolve to internal IP addresses before passing messages to ChatOpenAI or any LangChain model.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 3.7 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | Low | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data
Integrity
Technical Impact: Execute Unauthorized Code or Commands
Access Control
Technical Impact: Bypass Protection Mechanism
By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
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