CVE-2026-4786highCWE-77CWE-88

CVE-2026-4786: high-severity vulnerability in Python Software Foundation CPython

Incomplete mitigation of CVE-2026-4519, %action expansion for command injection to webbrowser.open()

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21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 7epss 0.3%
Mitgation of CVE-2026-4519 was incomplete. If the URL contained "%action" the mitigation could be bypassed for certain browser types the "webbrowser.open()" API could have commands injected into the underlying shell. See CVE-2026-4519 for details.
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Affected products
Python Software Foundation · CPython
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