Missing Ownership Verification in Key Revocation

openssl_encrypt versions before 1.4.0 contain a missing ownership verification vulnerability in the revoke_key method that allows authenticated clients to revoke any other client's key. Attackers can revoke arbitrary keys by providing a valid ML-DSA signature, bypassing the intended ownership restriction.

Casky was already ahead

This CVE exploits attack patterns that Casky's 283matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

CVE-2026-74877 represents a critical authentication bypass vulnerability in openssl_encrypt versions before 1.4.0. The revoke_key method fails to properly verify that the requesting client owns the key before processing revocation requests. While attackers must be authenticated to exploit this flaw, the vulnerability allows them to revoke cryptographic keys belonging to other clients by simply providing a valid ML-DSA signature—bypassing the intended ownership restriction. This affects any organization relying on openssl_encrypt for key management, particularly those managing multi-tenant environments or shared infrastructure where key isolation is essential for security boundaries.

Casky's 283 matching skills detect the attack patterns underlying this vulnerability by mapping to MITRE ATT&CK techniques TA0004 (Privilege Escalation) and TA0006 (Credential Access). Practitioners using Casky would observe detection signals indicating: (1) authenticated sessions performing key revocation operations on resources outside their ownership scope, triggering TA0004 patterns where legitimate permissions are misused to exceed intended access boundaries; and (2) systematic revocation of multiple keys across different client identities, suggesting TA0006 credential harvesting or denial-of-service tactics. Claude's extended reasoning analyzes the signature validation chain to distinguish between proper ownership verification and cases where authentication alone satisfies the revoke_key logic, surfacing the missing authorization check that security teams must remediate before the vulnerability reaches CISA KEV status.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

283 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-74877.

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

Access with Stolen Session Cookie

cryptography · low

Run

MITRE ATT&CK Techniques

TA0004 TA0006

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