CVE-2026-25528Public exploitNetwork attack vector

Trace-data exfiltration via injected replica URL

Published Feb 9, 2026 · Updated Feb 9, 2026

SSRF in LangChain LangSmith SDK tracing allows remote attackers to exfiltrate sensitive trace data through a crafted baggage header. RunTree.from_headers() and RunTree.fromHeaders() accept unvalidated api_url values in replica configurations, and post() and patch() send run data to every injected URL. Exposure requires an application to pass untrusted HTTP headers into distributed tracing or TracingMiddleware; resulting requests can disclose prompts, completions, and metadata.

CVSS severity5.8
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in LangChain LangSmith SDK tracing allows remote attackers to exfiltrate sensitive trace data through a crafted baggage header. RunTree.from_headers() and RunTree.fromHeaders() accept unvalidated api_url values in replica configurations, and post() and patch() send run data to every injected URL. Exposure requires an application to pass untrusted HTTP headers into distributed tracing or TracingMiddleware; resulting requests can disclose prompts, completions, and metadata.

The record

CVE
CVE-2026-25528
Published
Feb 9, 2026
Updated
Feb 9, 2026
Vendor
LangChain
Product
LangSmith SDK
Classifications
CWE-918, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 0.4.10, <0.6.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

LangChain · LangSmith SDKversion=>= 0.4.10, <0.6.3

Published CVSS scores

5.8GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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