CVE-2026-42770
June 10, 2026, 8:16 a.m.
3.7
Low
Description
Issue summary: When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42)
peer key, the peer key is not properly checked for the subgroup membership.
Impact summary: A malicious peer which presents an X9.42 key carrying the
victim's p and g parameters, a forged q = r (a small prime factor of the
cofactor (p−1)/q_local), and a public value Y of order r can recover the
victim's private key after a small number of key exchange attempts.
When EVP_PKEY_derive_set_peer() is called with a DHX (X9.42) peer key, the
subgroup membership check Y^q ≡ 1 (mod p) is performed using the peer's
own q parameter, not the local key's q. The peer's domain parameters are
then matched against the domain parameters of the private key, but the value
of q is not compared.
A malicious peer who presents an X9.42 key carrying the victim's p, g,
a forged q = r (a small prime factor of the cofactor), and a public
value Y of order r passes all checks. The shared secret then takes only
r distinct values, leaking priv mod r. Repeating for each small-prime
factor of the cofactor and combining via CRT recovers the full private
key (Lim–Lee / small-subgroup-confinement attack).
The realistic attack surface is narrow: principally CMP deployments with
long-lived RA/CA DHX keys and bespoke enterprise or government applications
using X9.42 DHX static keys with interactive protocols and therefore this
issue was assigned Low severity.
The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are affected by this
issue.
Product(s) Impacted
| Vendor | Product | Versions |
|---|---|---|
| Openssl |
|
|
Weaknesses
Common security weaknesses mapped to this vulnerability.
CWE-325
Missing Cryptographic Step
The product does not implement a required step in a cryptographic algorithm, resulting in weaker encryption than advertised by the algorithm.
*CPE(s)
Affected systems and software identified for this CVE.
| Type | Vendor | Product | Version | Update | Edition | Language | Software Edition | Target Software | Target Hardware | Other Information |
|---|---|---|---|---|---|---|---|---|---|---|
| a | openssl | openssl | 4.0 | / | / | / | / | / | / | / |
| a | openssl | openssl | 3.6 | / | / | / | / | / | / | / |
| a | openssl | openssl | 3.5 | / | / | / | / | / | / | / |
| a | openssl | openssl | 3.4 | / | / | / | / | / | / | / |
| a | openssl | openssl | 3.0 | / | / | / | / | / | / | / |
References
Tags
CVSS Score
CVSS Data - 3.1
- Attack Vector: NETWORK
- Attack Complexity: HIGH
- Privileges Required: NONE
- Scope: UNCHANGED
- Confidentiality Impact: LOW
- Integrity Impact: NONE
- Availability Impact: NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Timeline
Published: June 9, 2026, 5:17 p.m.
Last Modified: June 10, 2026, 8:16 a.m.
Last Modified: June 10, 2026, 8:16 a.m.
Status : Awaiting Analysis
CVE has been recently published to the CVE List and has been received by the NVD.
More infoSource
*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.