Streamlit up to 1.53.x on Windows UNC realpath server-side request forgery

Summaryinfo

A vulnerability was found in Streamlit up to 1.53.x on Windows. It has been classified as critical. This affects the function realpath of the component UNC Handler. Performing a manipulation results in server-side request forgery. This vulnerability is reported as CVE-2026-33682. The attacker must have access to the local network to execute the attack. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as critical, was found in Streamlit up to 1.53.x on Windows. This affects the function realpath of the component UNC Handler. The manipulation with an unknown input leads to a server-side request forgery vulnerability. CWE is classifying the issue as CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Streamlit is a data oriented application development framework for python. Streamlit Open Source versions prior to 1.54.0 running on Windows hosts have an unauthenticated Server-Side Request Forgery (SSRF) vulnerability. The vulnerability arises from improper validation of attacker-supplied filesystem paths. In certain code paths, including within the `ComponentRequestHandler`, filesystem paths are resolved using `os.path.realpath()` or `Path.resolve()` before sufficient validation occurs. On Windows systems, supplying a malicious UNC path (e.g., `\\attacker-controlled-host\share`) can cause the Streamlit server to initiate outbound SMB connections over port 445. When Windows attempts to authenticate to the remote SMB server, NTLMv2 challenge-response credentials of the Windows user running the Streamlit process may be transmitted. This behavior may allow an attacker to perform NTLM relay attacks against other internal services and/or identify internally reachable SMB hosts via timing analysis. The vulnerability has been fixed in Streamlit Open Source version 1.54.0.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-33682 since 03/23/2026. The exploitability is told to be difficult. Access to the local network is required for this attack. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available.

Upgrading to version 1.54.0 eliminates this vulnerability.

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Productinfo

Name

• Streamlit

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19
• 1.20
• 1.21
• 1.22
• 1.23
• 1.24
• 1.25
• 1.26
• 1.27
• 1.28
• 1.29
• 1.30
• 1.31
• 1.32
• 1.33
• 1.34
• 1.35
• 1.36
• 1.37
• 1.38
• 1.39
• 1.40
• 1.41
• 1.42
• 1.43
• 1.44
• 1.45
• 1.46
• 1.47
• 1.48
• 1.49
• 1.50
• 1.51
• 1.52
• 1.53

Website

• Product: https://github.com/streamlit/streamlit/

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