CVE-2025-61669Public exploitNetwork attack vector

Phishing redirect via triple-slash next parameter

Published May 5, 2026 · Updated May 5, 2026

Open redirect in Project Jupyter Jupyter Server 2.17.0 and earlier allows remote attackers to send users to external sites via crafted login URLs. LoginFormHandler._redirect_safe() treats a triple-slash next value as a permitted path and passes it to the redirect response without rejecting its external destination. Exploitation requires a user to follow the crafted login URL, after which the redirect can deliver a phishing site but does not directly compromise the server.

CVSS severity6.3
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Open redirect in Project Jupyter Jupyter Server 2.17.0 and earlier allows remote attackers to send users to external sites via crafted login URLs. LoginFormHandler._redirect_safe() treats a triple-slash next value as a permitted path and passes it to the redirect response without rejecting its external destination. Exploitation requires a user to follow the crafted login URL, after which the redirect can deliver a phishing site but does not directly compromise the server.

The record

CVE
CVE-2025-61669
Published
May 5, 2026
Updated
May 5, 2026
Vendor
Project Jupyter
Product
Jupyter Server
Classifications
CWE-601, T1566.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 5, 2026CVE publishedPublication date reported by the CVE source.
  2. May 5, 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=<= 2.17.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Project Jupyter · Jupyter Serverversion=<= 2.17.0

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.3GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:N/SA: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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-601URL Redirection to Untrusted Site ('Open Redirect')
T1566.002Spearphishing Link

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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