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Description

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().

PUBLISHED Reserved 2026-03-20 | Published 2026-03-20 | Updated 2026-04-13 | Assigner PSF




HIGH: 7.0CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Product status

Default status
unaffected

Any version before 3.13.13
affected

3.14.0 (python) before 3.14.4
affected

3.15.0a1 (python) before 3.15.0a8
affected

Credits

Seth Larson coordinator

Gregory P. Smith remediation reviewer

an7y reporter

References

www.openwall.com/lists/oss-security/2026/03/20/1

github.com/python/cpython/pull/143931 patch

github.com/python/cpython/issues/143930 issue-tracking

mail.python.org/.../thread/AY5NDSS433JK56Q7Q5IS7B37QFZVVOUS/ vendor-advisory

github.com/...ommit/43fe06b96f6a6cf5cfd5bdab20b8649374956866 patch

github.com/...ommit/82a24a4442312bdcfc4c799885e8b3e00990f02b patch

github.com/...ommit/9669a912a0e329c094e992204d6bdb8787024d76 patch

github.com/...ommit/ad4d5ba32af4d80b0dfa2ba9d8203bfb219e60a5 patch

github.com/...ommit/ceac1efc66516ac387eef2c9a0ce671895b44f03 patch

github.com/...ommit/cbba6119391112aba9c5aebf7b94aea447922c48 patch

github.com/...ommit/3681d47a440865aead912a054d4599087b4270dd patch

github.com/...ommit/591ed890270c5697b013bf637029fb3e6cd2d73e patch

github.com/...ommit/594b5a05dc9913880ac92eded440defbf32a28d1 patch

github.com/...ommit/89bfb8e5ed3c7caa241028f1a4eac5f6275a46a4 patch

github.com/...ommit/96fc5048605863c7b6fd6289643feb0e97edd96c patch

github.com/...ommit/cc023511238ad93ecc8796157c6f9139a2bb2932 patch

cve.org (CVE-2026-4519)

nvd.nist.gov (CVE-2026-4519)

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