[NEW] [high] CPython: Vulnerability allows Denial of Service

highCVE-2026-15308

A remote, anonymous attacker can exploit a vulnerability in CPython to conduct a Denial of Service attack.

CSIRTS triage

vendor: CPython product: CPython Denial of service

What: A vulnerability allows a remote attacker to conduct a Denial of Service attack.
Who is affected: Remote, anonymous attackers targeting CPython deployments.
Urgency: Remediation is urgent due to the high severity of the Denial of Service risk.
Action: Apply patches as they become available.

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

⚡ Watch CPython

Get an email when a new CPython advisory drops — max one per day, one-click unsubscribe.

Details

Source: CERT-Bund (BSI) Security Advisories (DE · national-cert · site)
Severity: high
Published: 2026-07-10
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-2026-2272

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-2026-153080.53% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 41% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-15308	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

unknownVulnerability in CPython (July 10, 2026)cert-fr-avis
highCVE-2026-15308: The incremental HTML parser (html.parser.HTMLParser) allows for CPU denial-of-service through …nvd

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.

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
low[UPDATE] [low] CPython: Vulnerability allows Denial of Servicecert-bund · 2026-07-10