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CVE-2026-4786

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

High7.0EPSS 0.29%
Published
Updated
Reserved
Assigned by
PSF

Description

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.

Scores

CVSS scores of CVE-2026-4786, by who scored it
Scored byCVSSScoreVector
PSFCNA (assigner)4.0High7.0CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
redhat-SADPADP (enrichment)3.1High7.1CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L
NVDNVD · Awaiting Analysis4.0High7.0CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS (exploitation in 30 days)
0.29% · top 78% of all CVEs (6 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: total
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.0.

Weakness

Affected products

  • Python Software Foundation · CPython

    • affected < 3.10.21
    • affected 3.11.0 – < 3.11.16
    • affected 3.12.0 – < 3.12.14
    • affected 3.13.0 – < 3.13.14
    • affected 3.14.0a1 – < 3.14.5rc1
    • affected 3.15.0a1 – < 3.15.0b1

References (58)

Sources

The same CVE in the primary databases and aggregators, to check against.

Badge for a README or a ticket

CVE-2026-4786 badge
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Record last updated .