The vulnerability is a server‑side request forgery in the background‑image endpoint of calibre’s e‑book viewer. By sending a crafted request to this endpoint, an attacker can cause calibre to perform blind GET requests to arbitrary URLs from the device it runs on, enabling the exfiltration of data that the application can reach. This weakness, classified as CWE‑918, allows information disclosure beyond the intended sandbox of the e‑book.

The issue affects the calibre e‑book manager developed by Kovidgoyal. All installations of calibre prior to version 9.6.0, regardless of operating system, are vulnerable because the flaw resides in the cross‑platform ebook viewer component. Users running 9.5.x or earlier remain at risk.

The CVSS score of 4.8 indicates a moderate risk, while the EPSS score of less than 1 % suggests a low probability of exploitation today. The recommendation is not listed in CISA’s KEV catalog. The description indicates that an attacker may trigger the SSRF by targeting the background‑image endpoint; however, the CVE entry does not specify the exact prerequisites or authentication required, so the precise attack surface is uncertain. Given the limited probability of exploitation and lack of public exploitation evidence, the threat is moderate but warrants timely remediation.