LangChain affected by SSRF via image_url token counting in ChatOpenAI.get_num_tokens_from_messages

## Server-Side Request Forgery (SSRF) in ChatOpenAI Image Token Counting ### Summary The `ChatOpenAI.get_num_tokens_from_messages()` method fetches arbitrary `image_url` values without validation when computing token counts for vision-enabled models. This allows attackers to trigger Server-Side Request Forgery (SSRF) attacks by providing malicious image URLs in user input. ### Severity **Low** - The vulnerability allows SSRF attacks but has limited impact due to: - Responses are not returned to the attacker (blind SSRF) - Default 5-second timeout limits resource exhaustion - Non-image responses fail at PIL image parsing ### Impact An attacker who can control image URLs passed to `get_num_tokens_from_messages()` can: - Trigger HTTP requests from the application server to arbitrary internal or external URLs - Cause the server to access internal network resources (private IPs, cloud metadata endpoints) - Cause minor resource consumption through image downloads (bounded by timeout) **Note:** This vulnerability occurs during token counting, which may happen outside of model invocation (e.g., in logging, metrics, or token budgeting flows). ### Details The vulnerable code path: 1. `get_num_tokens_from_messages()` processes messages containing `image_url` content blocks 2. For images without `detail: "low"`, it calls `_url_to_size()` to fetch the image and compute token counts 3. `_url_to_size()` performs `httpx.get(image_source)` on any URL without validation 4. Prior to the patch, there was no SSRF protection, size limits, or explicit timeout **File:** `libs/partners/openai/langchain_openai/chat_models/base.py` ### Patches The vulnerability has been patched in `langchain-openai==1.1.9` (requires `langchain-core==1.2.11`). The patch adds: 1. **SSRF validation** using `langchain_core._security._ssrf_protection.validate_safe_url()` to block: - Private IP ranges (RFC 1918, loopback, link-local) - Cloud metadata endpoints (169.254.169.254, etc.) - Invalid URL schemes 2. **Explicit size limits** (50 MB maximum, matching OpenAI's payload limit) 3. **Explicit timeout** (5 seconds, same as `httpx.get` default) 4. **Allow disabling image fetching** via `allow_fetching_images=False` parameter ### Workarounds If you cannot upgrade immediately: 1. **Sanitize input:** Validate and filter `image_url` values before passing messages to token counting or model invocation 2. **Use network controls:** Implement egress filtering to prevent outbound requests to private IPs

CVSS 3.1

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

Severity from

GitHub (reviewed advisory)

Weakness

CWE-918

Also known as

CVE-2026-26013, PYSEC-2026-2562

• github.com/langchain-ai/langchain/security/advisories/GHSA-2g6r-c272-w58r
• nvd.nist.gov/vuln/detail/CVE-2026-26013
• github.com/langchain-ai/langchain/commit/2b4b1dc29a833d4053deba4c2b77a3848c834565
• github.com/langchain-ai/langchain
• github.com/langchain-ai/langchain/releases/tag/langchain-core%3D%3D1.2.11