High 7.0Published Mar 20, 2026

CVE-2026-4519webbrowser.open() allows leading dashes in URLs

Updated under an hour ago (Oct 27, 2026, 5:23 PM ET)

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It affects Python Software Foundation CPython and 15 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Python Software Foundation CPython

Exploited in the last 30 days

The webbrowser.open() API would accept leading dashes in the URL which could be handled as command line options for certain web browsers. New behavior rejects leading dashes. Users are recommended to sanitize URLs prior to passing to webbrowser.open().

CVSS: 7.0 HIGH (v4.0, CNA)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
Weakness (CWE): CWE-20, CWE-88
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: PSF
NVD analysis: Modified
Record last updated: Aug 12, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Python Software Foundation CPython python_software_foundation:cpython (from the name)	before 3.10.21; from 3.11.0 before 3.11.16; from 3.12.0 before 3.12.14; from 3.13.0 before 3.13.13; from 3.14.0 before 3.14.4; from 3.15.0a1 before 3.15.0a8	CNA record
Red Hat Red Hat Enterprise Linux 10 redhat:enterprise_linux	from 0:3.12.12-3.el10_1.2 not affected; from 0:3.12.13-2.el10_2 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support redhat:enterprise_linux_eus	from 0:3.12.9-2.el10_0.8 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION redhat:rhel_els	from 0:2.6.6-70.el6_10.3 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 8.2 Advanced Update Support redhat:rhel_aus	from 0:3.6.8-24.el8_2.7 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On redhat:rhel_eus_long_life	from 0:3.6.8-39.el8_4.10 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 8.6 Telecommunications Update Service redhat:rhel_tus	from 0:3.6.8-47.el8_6.12 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions redhat:rhel_e4s	from 0:3.6.8-47.el8_6.12 not affected	CISA ADP
Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support redhat:rhel_eus	from 0:3.9.18-3.el9_4.12 not affected	CISA ADP
Red Hat RHEL-8 based Middleware Containers redhat:rhosemc	from 7.13.5-4.1777325677 not affected	CISA ADP
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References

References

https://github.com/python/cpython/pull/143931	patch, issue-tracking
https://github.com/python/cpython/issues/143930	issue-tracking, patch
https://mail.python.org/archives/list/security-announce@python.org/thread/AY5NDSS433JK56Q7Q5IS7B37QFZVVOUS/	vendor-advisory
https://github.com/python/cpython/commit/43fe06b96f6a6cf5cfd5bdab20b8649374956866	patch
https://github.com/python/cpython/commit/82a24a4442312bdcfc4c799885e8b3e00990f02b	patch
https://github.com/python/cpython/commit/9669a912a0e329c094e992204d6bdb8787024d76	patch
https://github.com/python/cpython/commit/ad4d5ba32af4d80b0dfa2ba9d8203bfb219e60a5	patch
https://github.com/python/cpython/commit/ceac1efc66516ac387eef2c9a0ce671895b44f03	patch
https://github.com/python/cpython/commit/cbba6119391112aba9c5aebf7b94aea447922c48	patch
https://github.com/python/cpython/commit/3681d47a440865aead912a054d4599087b4270dd	patch
1–10 of 25

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.