No exploitation reportedFix available

CVE-2026-4786

Q: Is CVE-2026-4786 actively exploited?

Active exploitation of CVE-2026-4786 has not been confirmed. Its EPSS score was 0.3% on 2026-10-24, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2026-4786?

CVE-2026-4786 has a CVSS v3 base score of 7.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L.

No exploitation reported by the sources we read.

Published2026-04-13
Fixed in3.14.5 · 3.13.14 · 3.12.14 · 3.11.16 · 3.10.21
WeaknessCWE-77 · CWE-88

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Mitgation of CVE-2026-4519 was incomplete. If the URL contained "%action" the mitigation could be bypassed for certain browser types the "webbrowser.open()" API could have commands injected into the underlying shell. See CVE-2026-4519 for details.

Timeline

dates in UTC

2026-04-1322:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-25 03:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-4786?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-4786?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV

python

Branch	Affected	Fixed in	Source
3.14	≥ 3.14.0, < 3.14.5	3.14.5	OSV
3.13	≥ 3.13.0, < 3.13.14	3.13.14	OSV
3.12	≥ 3.12.0, < 3.12.14	3.12.14	OSV
3.11	≥ 3.11.0, < 3.11.16	3.11.16	OSV
3.10	< 3.10.21	3.10.21	OSV

libpython

Branch	Affected	Fixed in	Source
3.14	≥ 3.14.0, < 3.14.5	3.14.5	OSV
3.13	≥ 3.13.0, < 3.13.14	3.13.14	OSV
3.12	≥ 3.12.0, < 3.12.14	3.12.14	OSV
3.11	≥ 3.11.0, < 3.11.16	3.11.16	OSV
3.10	< 3.10.21	3.10.21	OSV

python-min

Branch	Affected	Fixed in	Source
3.14	≥ 3.14.0, < 3.14.5	3.14.5	OSV
3.13	≥ 3.13.0, < 3.13.14	3.13.14	OSV
3.12	≥ 3.12.0, < 3.12.14	3.12.14	OSV
3.11	≥ 3.11.0, < 3.11.16	3.11.16	OSV
3.10	< 3.10.21	3.10.21	OSV

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

platform-pythonAlmaLinux:8all versions · fixed in 3.6.8-76.el8_10.alma.1and 6 other packages
python-unversioned-commandAlmaLinux:10all versions · fixed in 3.12.12-3.el10_1.3
python3AlmaLinux:10all versions · fixed in 3.12.13-2.el10_2and 7 other packages
python3AlmaLinux:9all versions · fixed in 3.9.25-7.el9_8and 7 other packages
python3AlmaLinux:9all versions · fixed in 3.9.25-3.el9_7.3and 7 other packages
python3.11AlmaLinux:9all versions · fixed in 3.11.13-9.el9_8and 6 other packages
python3.11AlmaLinux:9all versions · fixed in 3.11.13-5.3.el9_7and 6 other packages
python3.11AlmaLinux:8all versions · fixed in 3.11.13-7.el8_10and 7 other packages

7 more package ranges on OSV.dev

Vendor advisories

CVE-2026-4786 Red Hat Product Security1,968 products fixed · 106 known affected
python: cpython: Python: Arbitrary code execution via command injection in webbrowser.open() API
Cython.src as a component of Red Hat Enterprise Linux 8 · PyYAML.src as a component of Red Hat Enterprise Linux 8 · babel.src as a component of Red Hat Enterprise Linux 8 · +103 more
RHSA-2026:74674 Red Hat Product Security1 product fixed
Red Hat Security Advisory: Red Hat AI Base Images 3.4.3 (Neuron)
RHSA-2026:35838 Red Hat Product Security64 products fixed
Red Hat Security Advisory: python3 security update
RHSA-2026:30089 Red Hat Product Security2 products fixed
Red Hat Security Advisory: Red Hat AI Inference Server 3.3.5 (CUDA)
RHSA-2026:30088 Red Hat Product Security1 product fixed
Red Hat Security Advisory: Red Hat AI Inference Server 3.3.5 (ROCm)
RHSA-2026:30087 Red Hat Product Security3 products fixed
Red Hat Security Advisory: Red Hat AI Inference Server 3.3.5 (Spyre)

42 more advisories

Full record on NVD

Fix

Update python to 3.14.5 · 3.13.14 · 3.12.14 · 3.11.16 · 3.10.21
Vendor fix Red Hat Product Security RHSA-2026:74674 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:74674
Vendor fix Red Hat Product Security RHSA-2026:35838 · 64 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
Vendor fix Red Hat Product Security RHSA-2026:30089 · 2 productsFor more information visit https://access.redhat.com/errata/RHSA-2026:30089
Vendor fix Red Hat Product Security RHSA-2026:30088 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:30088
Vendor fix Red Hat Product Security RHSA-2026:30087 · 3 productsFor more information visit https://access.redhat.com/errata/RHSA-2026:30087
Vendor fix Red Hat Product Security RHSA-2026:30078 · 2 productsFor more information visit https://access.redhat.com/errata/RHSA-2026:30078

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

NVDCVE recordread 2026-10-23
CISA-ADPSSVC decisionnone2026-04-14
OpenCVESSVC decisionnone—
CNACVSS 4.07read 2026-10-23
CNACVSS 3.17.1read 2026-10-23
CNAweakness (CWE)CWE-77, CWE-88read 2026-10-23
FIRST EPSSEPSS score0.3 %2026-10-24
OSVaffected packages—
Microsoft MSRCadvisory—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L
CVSS 4.0 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/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
Published: 2026-04-13
Last Modified: 2026-08-13
NVD status: Awaiting Analysis
MSRC Title: Incomplete mitigation of CVE-2026-4519, %action expansion for command injection to webbrowser.open()

Frequently asked questions

What is CVE-2026-4786?

Is CVE-2026-4786 actively exploited?

Active exploitation of CVE-2026-4786 has not been confirmed. Its EPSS score was 0.3% on 2026-10-24, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-4786?

CVE-2026-4786 has a CVSS v3 base score of 7.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L.

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