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Vulnerabilities

Vulnerability · 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.

Published Mar 20, 2026 · catalog updated Aug 13, 2026 · Red Hat

Check if you run it

No confirmed exploitation is on record for CVE-2026-4519. EPSS is 0.41%. Act only if a listed version of Red Hat is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.41%
Remediation
Advisory link
Affected products
cpe python/python

A flaw was found in Python. The API, used to launch web browsers, does not properly sanitize input. This allows a remote attacker to craft a malicious URL containing leading dashes. When such a URL is opened, certain web browsers may interpret these dashes as command-line options, which could lead to unexpected behavior, information disclosure, or potentially arbitrary code execution, impacting the integrity of the system.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe python/python3.15.0

How to fix CVE-2026-4519

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-4519. EPSS is 0.41%. Act only if a listed version of Red Hat is installed.

Which versions are affected?

Compare what you have installed with 3.15.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-20: Improper Input Validation; CWE-88. EPSS 0.41%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 20, 2026 · NIST NVD

    Detected

    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().

  2. Aug 13, 2026 · NIST NVD

    Updated

    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().

Sources

  • CSAF AdvisoriesVendor advisoryRHSA-2026:9705:CVE-2026-4519

    A flaw was found in Python. The API, used to launch web browsers, does not properly sanitize input. This allows a remote attacker to craft a malicious URL containing leading dashes. When such a URL is opened, certain web browsers may interpret these dashes as command-line options

    security.access.redhat.com
  • CSAF AdvisoriesVendor advisoryRHSA-2026:9745:CVE-2026-4519

    A flaw was found in Python. The API, used to launch web browsers, does not properly sanitize input. This allows a remote attacker to craft a malicious URL containing leading dashes. When such a URL is opened, certain web browsers may interpret these dashes as command-line options

    security.access.redhat.com
  • CVE.orgVulnerability recordCVE-2026-4519

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-4519

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-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. New behavior rejects leading dashes. Users are recommended to sanitize URLs prior to passing to webbrowser.open().

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.