CVE-2026-34183: Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler

highCVSS 7.5CVE-2026-34183

CSIRTS triage

vendor: null product: nullOther

What: There is unbounded memory growth in the QUIC PATH_CHALLENGE handler.
Who is affected: Deployments using the QUIC protocol are affected by this issue.
Urgency: This vulnerability has a high severity with a CVSS score of 7.5, necessitating prompt action.
Action: Implement memory management best practices or update to a fixed version.

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

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 7.5
Published: 2026-06-09
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34183

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-2026-341830.51% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 40% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-34183	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

high[UPDATE] [high] OpenSSL: Multiple Vulnerabilitiescert-bund
unknownMultiple vulnerabilities in Tenable Identity Exposure (June 24, 2026)cert-fr-avis
unknownMultiple Vulnerabilities in Microsoft Products (June 22, 2026)cert-fr-avis

Recent advisories for Unbounded Memory Growth

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.

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highCVE-2026-56018: JavaScript::Minifier::XS versions before 0.16 for Perl leak memory on every call to minify(), …nvd · 2026-06-29