---
cve: "CVE-2026-9545"
severity: "HIGH"
cvss: 7.5
epss: "27%"
vendor: "curl"
kev: false
exploited: false
published: "2026-07-03 07:16:25"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-18T06:26:42+02:00"
---

# CVE-2026-9545

> 7.5 HIGH

## Beschreibung

In this scenario, libcurl first uses a proper HTTP/3 server for the initial
transfers, and when it makes a second transfer to the same site it has been
replaced by the attacker's impostor machine - without a valid certificate.

When libcurl returns to the hostname the second time with a cached SSL session
(`CURLOPT_SSL_SESSIONID_CACHE` is not disabled) and early data enabled (the
`CURLSSLOPT_EARLYDATA` bit is set in `CURLOPT_SSL_OPTIONS`), libcurl might
send off the second request's bytes on that new connection *before* enforcing
the certificate verification failure. Potentially leaking sensitive
information.

## CVSS-Vektor

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

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Keine | good |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- 68720b4837284335b2d63cb358f8f6ce65f5bc55 (Commit)

## Referenzen

- <https://curl.se/docs/CVE-2026-9545.json>
- <https://curl.se/docs/CVE-2026-9545.html>
- <https://hackerone.com/reports/3752888>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-9545) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_