webbrowser.open() allows leading dashes in URLs

MITRE NVD CVE.ORG JSON API Print: PDF PDF

Summary

CVECVE-2026-4519
StatePUBLISHED
AssignerPSF
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-20 15:16:24 UTC
Updated2026-04-16 14:53:22 UTC
DescriptionThe 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().

Risk And Classification

Primary CVSS: v4.0 7 HIGH from [email protected]

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/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: 0.000330000 probability, percentile 0.093440000 (date 2026-04-07)

Problem Types: CWE-20 | CWE-20 CWE-20 Improper Input Validation

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary7HIGHCVSS: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/C...
4.0CNACVSS7HIGHCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
3.1[email protected]Primary3.3LOWCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
Active
Confidentiality
High
Integrity
High
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/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

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Python Python All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Python Software Foundation CPython affected 3.13.13 python Not specified
CNA Python Software Foundation CPython affected 3.14.0 3.14.4 python Not specified
CNA Python Software Foundation CPython affected 3.15.0a1 3.15.0a8 python Not specified

References

ReferenceSourceLinkTags
github.com/python/cpython/commit/cbba6119391112aba9c5aebf7b94aea447922c48 [email protected] github.com Patch
github.com/python/cpython/commit/591ed890270c5697b013bf637029fb3e6cd2d73e [email protected] github.com Patch
github.com/python/cpython/commit/89bfb8e5ed3c7caa241028f1a4eac5f6275a46a4 [email protected] github.com Patch
github.com/python/cpython/commit/ceac1efc66516ac387eef2c9a0ce671895b44f03 [email protected] github.com Patch
github.com/python/cpython/commit/43fe06b96f6a6cf5cfd5bdab20b8649374956866 [email protected] github.com Patch
github.com/python/cpython/commit/96fc5048605863c7b6fd6289643feb0e97edd96c [email protected] github.com Patch
github.com/python/cpython/commit/cc023511238ad93ecc8796157c6f9139a2bb2932 [email protected] github.com Patch
github.com/python/cpython/commit/9669a912a0e329c094e992204d6bdb8787024d76 [email protected] github.com Patch
github.com/python/cpython/commit/82a24a4442312bdcfc4c799885e8b3e00990f02b [email protected] github.com Patch
github.com/python/cpython/commit/3681d47a440865aead912a054d4599087b4270dd [email protected] github.com Patch
github.com/python/cpython/commit/ad4d5ba32af4d80b0dfa2ba9d8203bfb219e60a5 [email protected] github.com Patch
www.openwall.com/lists/oss-security/2026/03/20/1 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com Mailing List, Third Party Advisory
mail.python.org/archives/list/[email protected]/thread/AY5NDSS433J... [email protected] mail.python.org Vendor Advisory
github.com/python/cpython/issues/143930 [email protected] github.com Issue Tracking, Patch
github.com/python/cpython/pull/143931 [email protected] github.com Issue Tracking, Patch
github.com/python/cpython/commit/594b5a05dc9913880ac92eded440defbf32a28d1 [email protected] github.com Patch
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Seth Larson (en)

CNA: Gregory P. Smith (en)

CNA: an7y (en)

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