CVE-2026-11564: libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. An easy handle that first uses default native CA

criticalCVSS 9.1CVE-2026-11564

libcurl keeps previously used connections in a connection pool for subsequent transfers to reuse if one of them matches the setup. An easy handle that first uses default native CA trust can continue trusting the native platform store after the application switches that same handle to custom CA material for a later transfer.

Details

Source: NVD Recent CVEs (US · database · site)
Severity: critical — CVSS 9.1
Published: 2026-07-03
Last updated: 2026-07-07
Exploitation: Not in CISA KEV at last sync

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-11564

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-2026-115640.61% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 45% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-11564	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

medium[UPDATE] [medium] cURL: Multiple vulnerabilitiescert-bund
unknownUSN-8525-1: curl vulnerabilitiesubuntu
unknownMultiple vulnerabilities in cURL and libcurl (June 24, 2026)cert-fr-avis

Recent advisories for libcurl keeps previously

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.

highCVE-2026-8932: libcurl would reuse a previously created connection even when some mTLS config related option h…nvd · 2026-07-03