What is the CVSS score of CVE-2026-21883?

CVE-2026-21883 has a CVSS 3.1 base score of 5.4 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Python are affected by CVE-2026-21883?

Organizations using Python. In should be aware of moderate risk from CVE-2026-21883 rated CVSS 5.4. Exploitation could compromise the security of affected deployments.. A patch is available.

Is there a public PoC exploit available for CVE-2026-21883?

Yes, a public proof-of-concept exploit is available for CVE-2026-21883. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-21883?

Within 30 days: Identify affected systems running Python. In and apply vendor patches as part of regular patch cycle. Vendor patch is available.

Python CVE-2026-21883

MEDIUM

Missing Origin Validation in WebSockets (CWE-1385)

2026-01-08 security-advisories@github.com

GHSA-793v-589g-574v

Python Bokeh Red Hat Suse

5.4

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

5.4 MEDIUM

AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

SUSE

MEDIUM

qualitative

Red Hat

5.4 MEDIUM

qualitative

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

PoC Detected

Mar 09, 2026 - 14:00 vuln.today

Public exploit code

Patch released

Mar 09, 2026 - 14:00 nvd

Patch available

CVE Published

Jan 08, 2026 - 02:15 nvd

MEDIUM 5.4

Blast Radius

ecosystem impact

† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth

16 pypi packages depend on bokeh (10 direct, 6 indirect)

Ecosystem-wide dependent count for version 3.8.2.

DescriptionGitHub Advisory

Bokeh is an interactive visualization library written in Python. In versions 3.8.1 and below, if a server is configured with an allowlist (e.g., dashboard.corp), an attacker can register a domain like dashboard.corp.attacker.com (or use a subdomain if applicable) and lure a victim to visit it. The malicious site can then initiate a WebSocket connection to the vulnerable Bokeh server. Since the Origin header (e.g., http://dashboard.corp.attacker.com/) matches the allowlist according to the flawed logic, the connection is accepted. Once connected, the attacker can interact with the Bokeh server on behalf of the victim, potentially accessing sensitive data, or modifying visualizations. This issue is fixed in version 3.8.2.

AnalysisAI

Bokeh versions 3.8.1 and below allow attackers to bypass Origin validation in WebSocket connections by registering domains that suffix-match allowlisted domains (e.g., dashboard.corp.attacker.com for allowlist entry dashboard.corp), enabling unauthorized server interaction. Public exploit code exists for this vulnerability, which could allow attackers to access sensitive data or modify visualizations on behalf of victims. …

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Vulnerability AssessmentAI

Risk Assessment	CVSS 5.4 (MEDIUM). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario	An attacker could exploit this vulnerability to compromise the affected system.
Remediation	A vendor patch is available — apply it immediately. … Detailed patch versions, workarounds, and compensating controls in full report.