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HIGH

CVE-2026-42784

CVSS v3

7.4

HIGH

EPSS Score

0.2 %

exploit probability, as of 2026-09-28

CISA KEV

No

known exploited

Exploitation

—

SSVC status

Description

A flaw was found in sequoia-openpgp. The library incorrectly infers key flags for older certificates when a key flags subpacket is missing, leading to a discrepancy in how key capabilities are viewed. This key flag confusion allows an attacker to bypass the back-signature check. Consequently, an attacker can illegitimately bind an arbitrary subkey to their own certificate and forge signatures, completely compromising cryptographic integrity.

Technical details

Published
2026-09-16
Last Modified
2026-09-16

Frequently asked questions

What is CVE-2026-42784?

A flaw was found in sequoia-openpgp. The library incorrectly infers key flags for older certificates when a key flags subpacket is missing, leading to a discrepancy in how key capabilities are viewed. This key flag confusion allows an attacker to bypass the back-signature check. Consequently, an attacker can illegitimately bind an arbitrary subkey to their own certificate and forge signatures, completely compromising cryptographic integrity.

Is CVE-2026-42784 actively exploited?

Active exploitation of CVE-2026-42784 has not been confirmed. Its EPSS score was 0.2% on 2026-09-28, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-42784?

CVE-2026-42784 has a CVSS v3 base score of 7.4 (HIGH severity).

Is CVE-2026-42784 affecting your environment?

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