# CVE-2026-107496: OpenSSL infinite loop in CMS encryption with EC certificates

Source: https://junglewise.ai/threats/cve-2026-107496-issue-summary-encrypting-a-cms-message-to-an-ec-certificate  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-107496 · Severity: info · Published 2026-11-10

OpenSSL's CMS encryption functions can hang indefinitely when given an EC certificate with an invalid group order of 1. An attacker who can supply a malicious recipient certificate to an application performing CMS encryption can cause that application to consume 100% CPU and become unresponsive, causing a denial of service.

Technologies: [OpenSSL](https://junglewise.ai/threats/technologies/openssl). Vendors: [OpenSSL](https://junglewise.ai/threats/vendors/openssl).

## Quick answers

**Is CVE-2026-107496 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-107496 being exploited in the wild.

**How severe is CVE-2026-107496?** Informational severity, published 10 November 2026.

**Which products and versions are affected?** OpenSSL 3.0, 3.5, 4.0, 4.1 (when enable-ec_explicit_curves is configured).

**Is there a fix for CVE-2026-107496?** No fixed version is recorded yet. Do not encrypt CMS messages to certificates with attacker-controlled EC parameters, or restrict the use of CMS encryption to trusted recipient certificates only. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-107496 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-107496?** Check whether you run OpenSSL at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix


Do not encrypt CMS messages to certificates with attacker-controlled EC parameters, or restrict the use of CMS encryption to trusted recipient certificates only.

## Technical details

CMS_encrypt() and CMS_encrypt_ex() fail to validate EC group order and enter an infinite loop when attempting to generate an ephemeral key for a group with order 1, since no nonzero scalar can be generated. The vulnerability requires an attacker-controlled recipient certificate and affects only applications that explicitly call these functions; normal TLS/QUIC usage is not impacted. The fix makes key generation fail cleanly instead of retrying indefinitely.

## Affected products

- OpenSSL OpenSSL 3.0, 3.5, 4.0, 4.1 (when enable-ec_explicit_curves is configured)

## Related threats

- [OpenSSL AES-GCM-SIV heap out-of-bounds read in EVP_CipherInit_ex](https://junglewise.ai/threats/cve-2026-95692-issue-summary-setting-an-aes-gcm-siv-iv-shorter-than-the-expected)
- [OpenSSL use-after-free in QUIC CRYPTO frame handling](https://junglewise.ai/threats/cve-2026-95691-issue-summary-a-retransmitted-quic-crypto-frame-can-release)
- [OpenSSL AES-GCM-SIV authentication tag bypass in AAD processing](https://junglewise.ai/threats/cve-2026-88823-issue-summary-the-aes-gcm-siv-implementation-treats-a-zero-length)
- [OpenSSL QUIC uninitialized stack data leak in peer detection](https://junglewise.ai/threats/cve-2026-88822-issue-summary-quic-when-performing-automated-peer-detection-may)
- [OpenSSL QUIC denial of service via NEW_CONNECTION_ID frame flooding](https://junglewise.ai/threats/cve-2026-84784-issue-summary-a-malicious-remote-peer-may-flood-the-local-quic)