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CVE-2026-4519

webbrowser.open() allows leading dashes in URLs

LOW
3.3
CVSS Score
Published: March 20, 2026 at 03:08 PM UTC
Updated: August 13, 2026 at 01:16 AM UTC
1 product affected across 1 vendorPython

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Severity
LOW3.3
Exploit prediction
EPSS 0.3%
SSVC
No known 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().

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Python· Python
95%
v < 3.10.21v < 3.13.133.11.0 ≤ v < 3.11.163.12.0 ≤ v < 3.12.143.13.0 ≤ v < 3.13.133.14.0 ≤ v < 3.14.43.15.0a1 ≤ v < 3.15.0a83.11.03.12.03.13.03.14.03.15.0 alpha13.15.0 alpha23.15.0 alpha33.15.0 alpha43.15.0 alpha53.15.0 alpha63.15.0 alpha73.15.0a1
Affected range stops below 3.10.21, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.11.16, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.12.14, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.13.13, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.14.4, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.15.0a8, so it looks safe — our inference, not a vendor statement

References (71)

Issue TrackingPatch
Source: [email protected]
https://github.com/python/cpython/issues/143930
PatchIssue Tracking
Source: [email protected]
https://github.com/python/cpython/pull/143931
Vendor Advisory
Source: [email protected]
https://mail.python.org/archives/list/[email protected]/thread/AY5NDSS433JK56Q7Q5IS7B37QFZVVOUS/
Patch
Source: cverecord
https://github.com/python/cpython/commit/43fe06b96f6a6cf5cfd5bdab20b8649374956866
Patch
Source: cverecord
https://github.com/python/cpython/commit/82a24a4442312bdcfc4c799885e8b3e00990f02b
Patch
Source: cverecord
https://github.com/python/cpython/commit/9669a912a0e329c094e992204d6bdb8787024d76
Patch
Source: cverecord
https://github.com/python/cpython/commit/ad4d5ba32af4d80b0dfa2ba9d8203bfb219e60a5
Patch
Source: cverecord
https://github.com/python/cpython/commit/ceac1efc66516ac387eef2c9a0ce671895b44f03

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

3.3LOW[email protected]
Attack Vector
LOCAL
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-20CWE-88

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