Unsafe Deserialization in langsmith (CVE-2026-45134)
Summary
Vulnerability in langsmith (CVE-2026-45134). Confidential information can be exposed externally. Exploitable via pull_prompt. Mitigation: upgrade to 0.8.0 or later.
Original description
The description as published by the source.
Description
The LangSmith SDK's prompt pull methods (pull_prompt / pull_prompt_commit in Python, pullPrompt / pullPromptCommit in JS/TS) fetch and deserialize prompt manifests from the LangSmith Hub. These manifests may contain serialized LangChain objects and model configuration that affect runtime behavior. When pulling a public prompt by owner/name identifier, the manifest content is controlled by an external party, but prior versions of the SDK did not distinguish this from pulling a prompt within the caller's own organization.
Prompt manifests can intentionally configure a model with a custom base URL, default headers, model name, or other constructor arguments. These are supported features, but they also mean the prompt contents should be treated as executable configuration rather than plain text. A prompt can also include serialized LangChain Runnable or PromptTemplate objects with attacker-controlled constructor kwargs, or secret references that, if secrets_from_env is enabled, read environment variables at deserialization time.
Applications are exposed when all of the following are true:
- The application calls
pull_promptorpull_prompt_commit(Python) orpullPromptorpullPromptCommit(JS/TS) with a publicowner/nameprompt identifier. - The prompt was published or modified by an untrusted or compromised account.
- The application uses the pulled prompt without independently validating its contents.
Applications that only pull promp…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-45134 has been found in langsmith.
Attackers can target a specific entry point like pull_prompt over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.1/10.
What to do: upgrade langsmith to 0.8.0 or later.
If unsure, ask your IT team or search "langsmith CVE-2026-45134" on the vendor's site.
CVE-2026-45134 (langsmith) — CWE-502 / CVSS v3 7.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: pull_prompt / pull_prompt_commit / pullPrompt / pullPromptCommit
Patched: 0.8.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Unsafe deserialization (CWE-502) exists in langsmith. Attackers reach the vulnerable code path via pull_prompt without authentication.
Check the vendor advisory for the affected versions of langsmith. Attack surface: pull_prompt / pull_prompt_commit / pullPrompt / pullPromptCommit.
Severity: High (CVSS 7.1/10). Confidential information can be exposed externally.
Update to 0.8.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'langsmith' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'langsmith' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
langsmithを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade langsmith to 0.8.0ステージング環境で 0.8.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com