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21Track

OpenSSL: Infinite Loop in CMS_encrypt() With an EC Group Order of 1

OpenSSL · CVE-2026-107496
0 news outlets0 CERTs and agencies0 research labs

Assessment: Track

SSVC decision points: exploitation none, automatable no, technical impact partial, deployment high.

What is it?

Issue summary: Encrypting a CMS message to an EC certificate whose group order is 1 may cause CMS_encrypt() or CMS_encrypt_ex() to loop indefinitely. Impact summary: An attacker able to supply the recipient certificate to an application performing CMS encryption can cause that application to loop indefinitely, consuming CPU and resulting in Denial of Service. CWE: CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') Description: CMS_encrypt() and CMS_encrypt_ex() encrypt a message to one or more recipient certificates and, for an EC recipient, generate an ephemeral key in the recipient's group. If the certificate declares a group order of 1, random scalar generation can only produce zero. The key generation routine then retries without limit while waiting for a nonzero private scalar, so the call never returns. The OpenSSL TLS and QUIC implementations do not use this path. An application is exposed only if it calls CMS_encrypt() or CMS_encrypt_ex() with a recipient certificate whose EC parameters are attacker-controlled. Certificates with normal EC group orders do not trigger the loop. OpenSSL 4.0 and later reject unknown explicit EC groups in default builds. These

Evidence

No coverage recorded yet.

Exploitation

  • Exploit code published (not verified by us)
  • Exploited in the wild (confirmed by a source)
  • Listed as known exploited (CISA KEV)
CVSS
Not scored
EPSS
–
First seen
1 d ago
Status
corroborated

All OpenSSL vulnerabilities