VulnerabilityModified
CVE-2026-4519
The webbrowser.open() API would accept leading dashes in the URL which could be handled as command line options for certain web browsers.
HIGH 7.0EPSS 0.31%
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.31%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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().
- CVSS 4.0
- 7.0 HIGHCVSS: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/M
- EPSS
- 0.31% probability · 23th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-20, CWE-88
- Affected
- python/python
- Source
- cna@python.org
References
- https://github.com/python/cpython/commit/3681d47a440865aead912a054d4599087b4270ddPatch
- https://github.com/python/cpython/commit/43fe06b96f6a6cf5cfd5bdab20b8649374956866Patch
- https://github.com/python/cpython/commit/591ed890270c5697b013bf637029fb3e6cd2d73ePatch
- https://github.com/python/cpython/commit/594b5a05dc9913880ac92eded440defbf32a28d1Patch
- https://github.com/python/cpython/commit/82a24a4442312bdcfc4c799885e8b3e00990f02bPatch
- https://github.com/python/cpython/commit/89bfb8e5ed3c7caa241028f1a4eac5f6275a46a4Patch
- https://github.com/python/cpython/commit/9669a912a0e329c094e992204d6bdb8787024d76Patch
- https://github.com/python/cpython/commit/96fc5048605863c7b6fd6289643feb0e97edd96cPatch
- https://github.com/python/cpython/commit/ad4d5ba32af4d80b0dfa2ba9d8203bfb219e60a5Patch
- https://github.com/python/cpython/commit/cbba6119391112aba9c5aebf7b94aea447922c48Patch
- https://github.com/python/cpython/commit/cc023511238ad93ecc8796157c6f9139a2bb2932Patch
- https://github.com/python/cpython/commit/ceac1efc66516ac387eef2c9a0ce671895b44f03Patch
- https://github.com/python/cpython/issues/143930Issue Tracking, Patch
- https://github.com/python/cpython/pull/143931Issue Tracking, Patch
- https://mail.python.org/archives/list/security-announce@python.org/thread/AY5NDSS433JK56Q7Q5IS7B37QFZVVOUS/Vendor Advisory
- http://www.openwall.com/lists/oss-security/2026/03/20/1Mailing List, Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:10065
- https://access.redhat.com/errata/RHSA-2026:10101
- https://access.redhat.com/errata/RHSA-2026:10102
- https://access.redhat.com/errata/RHSA-2026:10111
- https://access.redhat.com/errata/RHSA-2026:10140
- https://access.redhat.com/errata/RHSA-2026:10141
- https://access.redhat.com/errata/RHSA-2026:13812
- https://access.redhat.com/errata/RHSA-2026:16008
- https://access.redhat.com/errata/RHSA-2026:16009
- https://access.redhat.com/errata/RHSA-2026:16030
- https://access.redhat.com/errata/RHSA-2026:16174
- https://access.redhat.com/errata/RHSA-2026:19019
- https://access.redhat.com/errata/RHSA-2026:19064
- https://access.redhat.com/errata/RHSA-2026:19175
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.