How severe is CVE-2026-55408?

CVE-2026-55408 has a CVSS 4.0 base score of 8.4, rated high severity.

Is CVE-2026-55408 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-55408?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-55408 published?

CVE-2026-55408 was published on 2026-07-07 and last updated on 2026-07-08.

CVE-2026-55408

CVE-2026-55408 is a high-severity vulnerability with a CVSS 4.0 base score of 8.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-94.

Key facts

Severity: High (CVSS 4.0 base score 8.4)
EPSS exploit prediction: 0% (9th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-94
Published: 2026-07-07
Last modified: 2026-07-08

Description

Koodo Reader is an ebook reader. In version 2.3.0 and earlier, Koodo Reader is vulnerable to remote code execution through malicious EPUB files because the open-book IPC handler enables nodeIntegrationInSubFrames and EPUB chapter content is rendered with unsanitized innerHTML. An attacker can craft an EPUB book that, when imported and opened by the victim, instantiates a hidden iframe with Node.js API access and executes arbitrary operating system commands with the victim user's privileges. This issue is fixed in version 2.3.1.

Frequently asked questions

What is CVE-2026-55408?: Koodo Reader is an ebook reader. In version 2.3.0 and earlier, Koodo Reader is vulnerable to remote code execution through malicious EPUB files because the open-book IPC handler enables nodeIntegrationInSubFrames and EPUB chapter content is rendered with unsanitized innerHTML. An attacker can craft an EPUB book that, when imported and opened by the victim, instantiates a hidden iframe with Node.js API access and executes arbitrary operating system commands with the victim user's privileges. This issue is fixed in version 2.3.1.
How severe is CVE-2026-55408?: CVE-2026-55408 has a CVSS 4.0 base score of 8.4, rated high severity.
Is CVE-2026-55408 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-55408?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-55408 published?: CVE-2026-55408 was published on 2026-07-07 and last updated on 2026-07-08.

References

https://github.com/koodo-reader/koodo-reader/security/advisories/GHSA-mjr7-w4jq-2rq9

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