[UPDATE] [medium] CPython: Multiple vulnerabilities

mediumCVE-2026-12003 CVE-2026-3276

An attacker can exploit multiple vulnerabilities in CPython to manipulate files and trigger a Denial-of-Service condition.

CSIRTS triage

vendor: CPython product: CPython Denial of service

What: Multiple vulnerabilities allow an attacker to manipulate files and trigger a Denial-of-Service condition.
Who is affected: Deployments of CPython are affected.
Urgency: Remediation is medium urgency as the vulnerabilities can lead to service disruption.
Action: Update to the latest version of CPython.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: CERT-Bund (BSI) Security Advisories (DE · national-cert · site)
Severity: medium
Published: 2026-07-07
Exploitation: Not in CISA KEV at last sync
Language: Machine-translated to English — verify against the original

Original advisory: https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-1971

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-120030.14% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 3% of all scored CVEs.
Low exploitation riskCVE-2026-32760.49% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 39% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-12003	coverage & exploitation status	NVD · CVE.org
CVE-2026-3276	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

unknownUSN-8509-1: Python vulnerabilitiesubuntu
unknownVulnerability in CPython for Windows (June 22, 2026)cert-fr-avis
unknownCVE-2026-12003: CPython >3.11 Insecure Input Validation resulting in privilege escalationmsrc
unknownCVE-2026-3276: Potential DoS via quadratic complexity in unicodedata.normalize()msrc

Recent advisories for CPython

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

high[NEW] [high] CPython: Vulnerability allows Denial of Servicecert-bund · 2026-07-10
low[UPDATE] [low] CPython: Vulnerability allows file manipulationcert-bund · 2026-07-10
medium[UPDATE] [medium] CPython: Vulnerability allows bypassing security measurescert-bund · 2026-07-10
medium[UPDATE] [medium] Cpython: Multiple vulnerabilitiescert-bund · 2026-07-10
low[UPDATE] [low] CPython: Vulnerability allows unspecified attackcert-bund · 2026-07-10
medium[UPDATE] [medium] cPython: Vulnerability allows Denial of Servicecert-bund · 2026-07-10