How severe is CVE-2026-15638?

CVE-2026-15638 has a CVSS 4.0 base score of 9.1, rated critical severity.

Is CVE-2026-15638 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-2026-15638?

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

When was CVE-2026-15638 published?

CVE-2026-15638 was published on 2026-09-16 and last updated on 2026-09-18.

CVE-2026-15638

CVE-2026-15638 is a critical-severity vulnerability with a CVSS 4.0 base score of 9.1. 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-327.

Key facts

Severity: Critical (CVSS 4.0 base score 9.1)
EPSS exploit prediction: 0% (9th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-327
Published: 2026-09-16
Last modified: 2026-09-18

Description

An unauthenticated user with access to Secret Server could leverage a padding oracle to decrypt or encrypt data using one of the server's cryptographic keys. The key itself is not exposed.

Frequently asked questions

What is CVE-2026-15638?: An unauthenticated user with access to Secret Server could leverage a padding oracle to decrypt or encrypt data using one of the server's cryptographic keys. The key itself is not exposed.
How severe is CVE-2026-15638?: CVE-2026-15638 has a CVSS 4.0 base score of 9.1, rated critical severity.
Is CVE-2026-15638 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-2026-15638?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-15638 published?: CVE-2026-15638 was published on 2026-09-16 and last updated on 2026-09-18.

References

https://delinea.com/security-advisories

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