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CVE Record

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

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().

HighCVSS 7.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-4519 affects Python's webbrowser.open() handling of URLs that start with dashes. In some browser integrations, that input could be interpreted as command-line options, creating a path to serious compromise when attacker-controlled input is opened.

Executive priority

Prioritize remediation for applications that open user-supplied links through Python automation or desktop workflows. This is high severity but not currently shown as actively exploited in the provided sources.

Technical view

The issue is improper input validation and argument injection in CPython's webbrowser.open(). The fixed behavior rejects leading-dash URLs. The CVSS 3.1 score is 7.1, with network attack vector, high complexity, no privileges, required user interaction, and high confidentiality and integrity impact.

Likely exposure

Exposure is most likely in Python applications or scripts that pass user-controlled or external URLs into webbrowser.open(). The source record names CPython and affected version entries 0, 3.14.0, and 3.15.0a1, with other versions not established here.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation. Successful abuse appears conditional: an attacker must influence the URL, the application must call webbrowser.open(), and the selected browser path must treat leading dashes as options.

Researcher notes

Key research focus is the boundary between Python URL validation and browser command-line parsing. Evidence supports argument injection risk, but affected browser-specific behaviors, exact fixed release mapping, and real-world exploitation are not fully detailed in the bundle.

Mitigation direction

  • Apply CPython or operating-system vendor security updates when available.
  • Reject or sanitize URLs beginning with dashes before calling webbrowser.open().
  • Audit application paths that open external or user-supplied URLs.
  • Follow Python Software Foundation and distro advisories for fixed release guidance.

Validation and detection

  • Inventory CPython versions used in servers, desktops, build agents, and packaged tools.
  • Review code for webbrowser.open() calls receiving external input.
  • Confirm patched runtimes reject leading-dash URL values.
  • Check vendor advisory status for platform packages such as Red Hat builds.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-20: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cwe · medium confidence lookup

CWE-88: Command execution behavior lookup

Command injection weaknesses can lead defenders to review execution techniques and command interpreter telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2026-4519 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.1 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
3ADP providers
56Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: total

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.1CVSS 3.1HighCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L1.65.5redhat-SADP
7CVSS 4.0HighCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N——PSF

Vulnerability scoring details

Base CVSS 4.0 score

7High
CVSS 4.0 vector shape for CVE-2026-4519Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: 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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPpython: Python: Command-line option injection in webbrowser.open() via crafted URLs
other:Red Hat severity ratingcvssV3_1
  • 2026-03-20T16:02:13.494Z: Reported to Red Hat.
  • 2026-03-20T15:08:32.576Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Python Software FoundationCPython0, 3.14.0, 3.15.0a1unaffected
Weakness

CWE details

CWE-20CWE-88

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-20 · source CWE mapping

Improper Input Validation

Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-88 · source CWE mapping

Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')

Improper Neutralization of Argument Delimiters in a Command ('Argument Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs