# CVE-2026-4519: webbrowser.open() allows leading dashes in URLs > Attackers can inject command-line options into web browsers via webbrowser.open() by using URLs with leading dashes, potentially executing arbitrary commands. - **Severity:** High 7.0 (`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`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Local or same network only - **Victim action needed:** A user has to click or open something - **Fix available:** Yes - **Published:** 20 Mar 2026 - **Updated:** 13 Aug 2026 - **Also known as:** ALPINE-CVE-2026-4519, ALSA-2026:6256, ALSA-2026:6281, ALSA-2026:6283, ALSA-2026:6285, ALSA-2026:6286, ALSA-2026:6473, ALSA-2026:6766, AZL-109713, AZL-80490, BELL-CVE-2026-4519, CLSA-2026-1775654402, CLSA-2026-1776169648, CLSA-2026-1777456062, CLSA-2026-1777946712, CLSA-2026-1777946871, CLSA-2026-1778000974, CLSA-2026-1778002076, CLSA-2026-1778002331, CLSA-2026-1778015238, DEBIAN-CVE-2026-4519, ECHO-d547-7bae-8442, GHSA-rm92-fj5q-mpj5, MINI-3pq4-3wq9-67fq, MINI-4fv2-9g59-92c8, MINI-89gq-r9gv-h3x4, MINI-mm75-g8vh-j5r4, MINI-vcpx-376x-9c82, PSF-2026-14, RHSA-2026:10101, RHSA-2026:10102, RHSA-2026:10111, RHSA-2026:6016, RHSA-2026:6035, RHSA-2026:6256, RHSA-2026:6281, RHSA-2026:6283, RHSA-2026:6285, RHSA-2026:6286, RHSA-2026:6473, RHSA-2026:6766, RHSA-2026:7010, RHSA-2026:7244, RHSA-2026:9042, RHSA-2026:9260, RHSA-2026:9261, RHSA-2026:9262, RHSA-2026:9289, RHSA-2026:9354, RHSA-2026:9386, RHSA-2026:9387, RHSA-2026:9591, RHSA-2026:9614, RHSA-2026:9621, RHSA-2026:9705, RHSA-2026:9745, RLSA-2026:6281, RLSA-2026:6283, RLSA-2026:6285, RLSA-2026:6286, RLSA-2026:6473, RLSA-2026:6766, ROOT-OS-DEBIAN-11-CVE-2026-4519, UBUNTU-CVE-2026-4519 ## What is CVE-2026-4519? CVE-2026-4519 is a high-severity command injection vulnerability in Python Python, published on 20 Mar 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link. ### Official 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(). Weakness: CWE-88 (Improper Neutralization of Argument Delimiters in a Command), CWE-20 (Improper Input Validation) ## Which versions are affected by CVE-2026-4519? It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `python-unversioned-command` | AlmaLinux:10 | All versions | 3.12.12-3.el10_1.2 | | `platform-python` | AlmaLinux:8 | All versions | 3.6.8-75.el8_10.alma.1 | | `platform-python-debug` | AlmaLinux:8 | All versions | 3.6.8-75.el8_10.alma.1 | | `platform-python-devel` | AlmaLinux:8 | All versions | 3.6.8-75.el8_10.alma.1 | | `python3-idle` | AlmaLinux:8 | All versions | 3.6.8-75.el8_10.alma.1 | | `python3-libs` | AlmaLinux:8 | All versions | 3.6.8-75.el8_10.alma.1 | | `python3-test` | AlmaLinux:8 | All versions | 3.6.8-75.el8_10.alma.1 | | `python3-tkinter` | AlmaLinux:8 | All versions | 3.6.8-75.el8_10.alma.1 | | `python3.11` | AlmaLinux:8 | All versions | 3.11.13-6.el8_10 | | `python3.11-debug` | AlmaLinux:8 | All versions | 3.11.13-6.el8_10 | | `python3.11-devel` | AlmaLinux:8 | All versions | 3.11.13-6.el8_10 | | `python3.11-idle` | AlmaLinux:8 | All versions | 3.11.13-6.el8_10 | | `python3.11-libs` | AlmaLinux:8 | All versions | 3.11.13-6.el8_10 | | `python3.11-rpm-macros` | AlmaLinux:8 | All versions | 3.11.13-6.el8_10 | | `python3.11-test` | AlmaLinux:8 | All versions | 3.11.13-6.el8_10 | | `python3.11-tkinter` | AlmaLinux:8 | All versions | 3.11.13-6.el8_10 | | `python3.12` | AlmaLinux:8 | All versions | 3.12.12-4.el8_10 | | `python3.12-debug` | AlmaLinux:8 | All versions | 3.12.12-4.el8_10 | | `python3.12-devel` | AlmaLinux:8 | All versions | 3.12.12-4.el8_10 | | `python3.12-idle` | AlmaLinux:8 | All versions | 3.12.12-4.el8_10 | | `python3.12-libs` | AlmaLinux:8 | All versions | 3.12.12-4.el8_10 | | `python3.12-rpm-macros` | AlmaLinux:8 | All versions | 3.12.12-4.el8_10 | | `python3.12-test` | AlmaLinux:8 | All versions | 3.12.12-4.el8_10 | | `python3.12-tkinter` | AlmaLinux:8 | All versions | 3.12.12-4.el8_10 | | `python-unversioned-command` | AlmaLinux:9 | All versions | 3.9.25-3.el9_7.2 | | `python3` | AlmaLinux:9 | All versions | 3.9.25-3.el9_7.2 | | `python3-debug` | AlmaLinux:9 | All versions | 3.9.25-3.el9_7.2 | | `python3-devel` | AlmaLinux:9 | All versions | 3.9.25-3.el9_7.2 | | `python3-idle` | AlmaLinux:9 | All versions | 3.9.25-3.el9_7.2 | | `python3-libs` | AlmaLinux:9 | All versions | 3.9.25-3.el9_7.2 | | `python3-test` | AlmaLinux:9 | All versions | 3.9.25-3.el9_7.2 | | `python3-tkinter` | AlmaLinux:9 | All versions | 3.9.25-3.el9_7.2 | | `python3.11` | AlmaLinux:9 | All versions | 3.11.13-5.2.el9_7 | | `python3.11-debug` | AlmaLinux:9 | All versions | 3.11.13-5.2.el9_7 | | `python3.11-devel` | AlmaLinux:9 | All versions | 3.11.13-5.2.el9_7 | | `python3.11-idle` | AlmaLinux:9 | All versions | 3.11.13-5.2.el9_7 | | `python3.11-libs` | AlmaLinux:9 | All versions | 3.11.13-5.2.el9_7 | | `python3.11-test` | AlmaLinux:9 | All versions | 3.11.13-5.2.el9_7 | | `python3.11-tkinter` | AlmaLinux:9 | All versions | 3.11.13-5.2.el9_7 | | `python3.12` | AlmaLinux:9 | All versions | 3.12.12-4.el9_7.2 | Products: Python Python. ## How do I fix CVE-2026-4519? Apply the vendor's patch. ## Is CVE-2026-4519 being exploited? There is no known exploitation of CVE-2026-4519 in the wild and no public exploit code. ## Other vulnerabilities in Python Python - [CVE-2008-5031](https://insights.sbomify.com/CVE-2008-5031/): Integer overflow in n/a (critical 10.0) - [CVE-2014-4650](https://insights.sbomify.com/CVE-2014-4650/): Path traversal in n/a (critical 9.8) - [CVE-2016-5636](https://insights.sbomify.com/CVE-2016-5636/): Integer overflow in n/a (critical 9.8) - [CVE-2007-4559](https://insights.sbomify.com/CVE-2007-4559/): Path traversal in n/a (critical 9.8) - [CVE-2017-17522](https://insights.sbomify.com/CVE-2017-17522/): Command injection in n/a (high 8.8) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-4519 and fix it if it is affected. What it is: CVE-2026-4519 is a high-severity command injection vulnerability in Python Python, published on 20 Mar 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link. Exploitation: There is no known exploitation of CVE-2026-4519 in the wild and no public exploit code. Affected product: Python Python. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-4519/ (Markdown: https://insights.sbomify.com/CVE-2026-4519/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4519 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4519 - OSV: https://osv.dev/vulnerability/CVE-2026-4519 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-4519/ Summaries are generated and may contain mistakes; the official description above is the record.