CVE-2026-4786highCWE-77 CWE-88

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

21Vexday Risk Score

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

ssvc Trackcvss 7epss 0.3%

exploitation probability

0.3%top 78% of all CVEs

observed exploitation

nono source reports it

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

References