CVE-2026-4519: webbrowser.open() allows leading dashes in URLs
Vulnerability summary
CVE-2026-4519 is a high (CVSS 7.1) Improper Input Validation vulnerability in python software foundation cpython. EPSS estimates a 0.31% chance of exploitation in the next 30 days, higher than 24.3% of scored vulnerabilities.
Not severe (CVSS 7, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 32 · Related 24Timeline
- 20-03-2026PublishedVulnerability first disclosed.
- 13-08-2026Last modifiedVulnerability information updated.
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().
CVSS metrics
11 scores · 8 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated7.0HighCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- OSV · WolfiEcosystem advisory · calculated7.0HighCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- OSV · ChainguardEcosystem advisory · calculated7.0HighCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- NVDNIST7.0HighCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/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
- OSV · AlpineEcosystem advisory · calculated3.3LowCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:NDiffers
- OSV · Red hatEcosystem advisory · calculated7.1HighCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L
- OSV · UbuntuEcosystem advisory · calculated3.3LowCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:NDiffers
- OSV · DebianEcosystem advisory · calculated3.3LowCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:NDiffers
- NVDNIST3.3LowCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:NDiffers
EPSS trend
Probability
0.31%
Chance of exploitation in the next 30 days
Percentile
24%
Versus all other CVEs
30-day change
Decrease -0.08 pp
From 0.39% on 04-10-2026
Known exploited
Compare KEV catalogsNot in the CISA KEV catalog.
Not in the ENISA CNW catalog.
Not in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
- CWE-88Improper Neutralization of Argument Delimiters in a CommandThe product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.
Affected systems
Known conditions: local access, no authentication, user interaction (CVSS vector). Other conditions: not stated in public data.
Redhat44 products
- platform-python< 0:3.6.8-75.el8_10 | < 0:3.6.8-51.el8_8.14 | < 0:3.6.8-47.el8_6.12 | < 0:3.6.8-24.el8_2.7 | < 0:3.6.8-39.el8_4.10
- platform-python-debug< 0:3.6.8-75.el8_10 | < 0:3.6.8-51.el8_8.14 | < 0:3.6.8-47.el8_6.12 | < 0:3.6.8-24.el8_2.7 | < 0:3.6.8-39.el8_4.10
- platform-python-devel< 0:3.6.8-75.el8_10 | < 0:3.6.8-51.el8_8.14 | < 0:3.6.8-47.el8_6.12 | < 0:3.6.8-24.el8_2.7 | < 0:3.6.8-39.el8_4.10
- python< 0:2.6.6-70.el6_10.3 | < 0:2.7.5-94.el7_9.4
- python-debug< 0:2.7.5-94.el7_9.4
Ubuntu14 products
- jythonAll versions (No fix recorded)
- pypy3All versions (No fix recorded)
- python2.7All versions (No fix recorded)
- python3.10< 3.10.12-1~22.04.16
- python3.11All versions (No fix recorded)
Chainguard6 products
- python-3.10< 3.10.20-r1
- python-3.11< 3.11.15-r1
- python-3.12< 3.12.13-r1
- python-3.13< 3.13.12-r5
- python-3.14< 3.14.3-r5
Debian5 products
- jythonAll versions (No fix recorded)
- pypy3All versions (No fix recorded) | < 7.3.22+dfsg-1
- python3.11< 3.11.2-6+deb12u8
- python3.13< 3.13.14-1 | < 3.13.5-2+deb13u2
- python3.14< 3.14.4-1
Wolfi5 products
- python-3.10< 3.10.20-r1
- python-3.11< 3.11.15-r1
- python-3.12< 3.12.13-r1
- python-3.13< 3.13.12-r5
- python-3.14< 3.14.3-r5
Alpine1 product
- python3< 3.12.14-r0
Python1 product
- python< 3.13.13 | ≥ 3.14.0, < 3.14.4 | 3.15.0:alpha1 | 3.15.0:alpha2 | 3.15.0:alpha3 | 3.15.0:alpha4 | 3.15.0:alpha5 | 3.15.0:alpha6 | 3.15.0:alpha7
Python software foundation1 product
- cpython< 3.10.21 | ≥ 3.11.0, < 3.11.16 | ≥ 3.12.0, < 3.12.14 | ≥ 3.13.0, < 3.13.13 | ≥ 3.14.0, < 3.14.4 | ≥ 3.15.0a1, < 3.15.0a8
8 vendors · 77 products
References
109 links- mail.python.org/archives/list/security-announce@python.org/thread/AY5NDSS433JK56Q7Q5IS7B37QFZVVOUS/Vendor AdvisoryARTICLEREPORTAdvisory
Show all 100 references
- images.redhat.comARTICLE
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