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Vulnerability details: VCID-pjk6-29bj-4kg1
Vulnerability ID VCID-pjk6-29bj-4kg1
Aliases CVE-2026-42557
GHSA-mqcg-5x36-vfcg
Summary jupyterlab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. Prior to 4.5.7, JupyterLab's HTML sanitizer allowlists data-commandlinker-command and data-commandlinker-args on button elements, while CommandLinker listens for all click events on document.body and executes the named command without checking whether the element came from trusted JupyterLab UI. A notebook with a pre-saved HTML cell output containing a deceptive button can trigger arbitrary JupyterLab commands - including arbitrary code execution - on a single user click, without any code being submitted for execution by the user. This vulnerability is fixed in 4.5.7.
Status Published
Exploitability 0.5
Weighted Severity 8.6
Risk 4.3
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
epss 0.00079 https://api.first.org/data/v1/epss?cve=CVE-2026-42557
epss 0.00079 https://api.first.org/data/v1/epss?cve=CVE-2026-42557
cvssv3.1_qr HIGH https://github.com/advisories/GHSA-mqcg-5x36-vfcg
cvssv3.1 9.6 https://github.com/jupyterlab/jupyterlab
cvssv4 8.6 https://github.com/jupyterlab/jupyterlab
generic_textual HIGH https://github.com/jupyterlab/jupyterlab
cvssv3.1 9.6 https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg
cvssv3.1_qr HIGH https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg
cvssv4 8.6 https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg
generic_textual HIGH https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg
ssvc Track https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg
cvssv3.1 9.6 https://jupyterlab.readthedocs.io/en/latest/user/commands.html#commands-in-markdown-files
cvssv4 8.6 https://jupyterlab.readthedocs.io/en/latest/user/commands.html#commands-in-markdown-files
generic_textual HIGH https://jupyterlab.readthedocs.io/en/latest/user/commands.html#commands-in-markdown-files
cvssv3.1 9.6 https://nvd.nist.gov/vuln/detail/CVE-2026-42557
cvssv4 8.6 https://nvd.nist.gov/vuln/detail/CVE-2026-42557
generic_textual HIGH https://nvd.nist.gov/vuln/detail/CVE-2026-42557
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2026-42557
https://github.com/jupyterlab/jupyterlab
https://jupyterlab.readthedocs.io/en/latest/user/commands.html#commands-in-markdown-files
https://nvd.nist.gov/vuln/detail/CVE-2026-42557
GHSA-mqcg-5x36-vfcg https://github.com/advisories/GHSA-mqcg-5x36-vfcg
GHSA-mqcg-5x36-vfcg https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H Found at https://github.com/jupyterlab/jupyterlab
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://github.com/jupyterlab/jupyterlab
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H Found at https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:T/P:M/B:A/M:M/D:T/2026-05-14T17:57:35Z/ Found at https://github.com/jupyterlab/jupyterlab/security/advisories/GHSA-mqcg-5x36-vfcg
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H Found at https://jupyterlab.readthedocs.io/en/latest/user/commands.html#commands-in-markdown-files
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://jupyterlab.readthedocs.io/en/latest/user/commands.html#commands-in-markdown-files
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2026-42557
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://nvd.nist.gov/vuln/detail/CVE-2026-42557
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.23455
EPSS Score 0.00079
Published At June 11, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-06-11T16:44:16.769333+00:00 Vulnrichment Import https://github.com/cisagov/vulnrichment/blob/develop/2026/42xxx/CVE-2026-42557.json 38.6.0