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Fencer Vulns
low 3.7

CVE-2026-42770 json

FFC-DH Peer Validation Uses Attacker-Supplied q

published 2026-06-09 5 mo ago modified 2026-08-13 2 mo ago also EUVD-2026-35487 , GHSA-3cxm-476w-ghm2 , JLSEC-2026-1142

cvss
3.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 43%
public exploits
0
none known

Summary

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, 3.1.2 and 3.0 are affected by this issue.

Patch / fix

  • julia AppBundler 1.0.1
  • julia OpenSSL_jll 3.5.7+0
  • OpenSSL OpenSSL 3.0.21, 3.4.6, 3.5.7, 3.6.3, 4.0.1
  • openssl Debian 12 3.0.20-1~deb12u2
  • openssl Debian 13 3.5.6-1~deb13u2
  • openssl Debian 14 3.6.3-1

debian advisories DEBIAN-CVE-2026-42770

  • openssl Ubuntu 22.04 LTS 3.0.2-0ubuntu1.25
  • openssl Ubuntu 24.04 LTS 3.0.13-0ubuntu3.11
  • openssl Ubuntu 25.10 3.5.3-1ubuntu3.4
  • openssl Ubuntu 26.04 LTS 3.5.5-1ubuntu3.2
  • openssl Ubuntu Pro FIPS-updates 22.04 LTS 3.0.2-0ubuntu1.25+Fips1
  • openssl-fips Ubuntu Pro FIPS-updates 24.04 LTS 3.0.13-0ubuntu3.12+Fips1

ubuntu advisories UBUNTU-CVE-2026-42770

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • bootupd hummingbird 1 0.3.2-1.hum1
  • rust-bootupd hummingbird 1 0.3.2-1.hum1
  • ruby3.4 hummingbird 1 3.4.10-31.7.hum1
  • ruby3.4-libs hummingbird 1 3.4.10-31.7.hum1
  • ruby3.4-bundled-gems hummingbird 1 3.4.10-31.7.hum1
  • ruby3.4-default-gems hummingbird 1 3.4.10-31.7.hum1
  • ruby4.0 hummingbird 1 4.0.6-37.3.hum1
  • ruby4.0-libs hummingbird 1 4.0.6-37.3.hum1

red hat advisories RHSA-2026:67551RHSA-2026:62790RHSA-2026:62563RHSA-2026:62562RHSA-2026:55543RHSA-2026:42825

  • openssl-3 SLE Module for Basesystem 15 SP7 3.2.3-150700.5.36.1
  • openssl-3 SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +3 more 3.0.8-150400.4.87.1
  • openssl-3 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 3.5.0-160000.8.1
  • openssl-3 SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS +1 more 3.0.8-150500.5.66.1
  • openssl-3 Linux Micro 6.1 3.1.4-slfo.1.1_10.1
  • openssl-3 Linux Micro 6.0 3.1.4-14.1
  • openssl-3 SLES for SAP 15 SP6, SLES 15 SP6-LTSS 3.1.4-150600.5.53.1

suse advisories SUSE-SU-2026:2648-1SUSE-SU-2026:2598-1SUSE-SU-2026:22251-1SUSE-SU-2026:22315-1SUSE-SU-2026:2397-1SUSE-SU-2026:2393-1

  • openssl-3 openSUSE Leap 16.0 3.5.0-160000.8.1
  • openssl-3 openSUSE Tumbleweed 3.5.3-6.1

opensuse advisories openSUSE-SU-2026:21005-1openSUSE-SU-2026:11023-1

  • openssl AlmaLinux 10 1:3.5.5-4.el10_2.alma.1
  • openssl-libs AlmaLinux 10 1:3.5.5-4.el10_2.alma.1
  • openssl-perl AlmaLinux 10 1:3.5.5-4.el10_2.alma.1
  • openssl AlmaLinux 9 1:3.5.5-4.el9_8
  • openssl-libs AlmaLinux 9 1:3.5.5-4.el9_8
  • openssl-perl AlmaLinux 9 1:3.5.5-4.el9_8

almalinux advisories ALSA-2026:25237ALSA-2026:25239

  • openssl Rocky Linux 10 1:3.5.5-4.el10_2
  • openssl Rocky Linux 9 1:3.5.5-4.el9_8

rocky linux advisories RLSA-2026:25237RLSA-2026:25239

  • openssl Alpine 3.21 3.3.7-r1
  • openssl Alpine 3.24, Alpine 3.23, Alpine 3.22 3.5.7-r0

alpine advisories ALPINE-CVE-2026-42770

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • openssl Azure Linux 3.0 3.3.7-4
  • edk2 Azure Linux 3.0 20240524git3e722403cd16-20

azure linux advisories AZL-92843AZL-95910

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-42770 updated cvss 5.9

openssl: FFC-DH Peer Validation Uses Attacker-Supplied q

  • Red Hat Enterprise Linux 6 openssl, openssl-perl Red Hat Enterprise Linux 7 ovmf, OVMF, AAVMF Red Hat Enterprise Linux 8 edk2, shim, openssl, shim-x64, edk2-ovmf, shim-aa64, +9 more Red Hat Enterprise Linux 9 edk2, shim, shim-x64, edk2-ovmf, shim-aa64, edk2-tools, +4 more Red Hat Enterprise Linux 10 edk2, shim, shim-unsigned-x64, shim-unsigned-aarch64 Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.17 cert-manager/cert-manager-operator-rhel9 1791788287, cert-manager/jetstack-cert-manager-rhel9 1791371069, cert-manager/cert-manager-operator-bundle 1791970484, cert-manager/jetstack-cert-manager-acmesolver-rhel9 1791371080
    fixed: vendor fix RHSA-2026:82888
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 cert-manager/cert-manager-operator-rhel9 1789029076, cert-manager/jetstack-cert-manager-rhel9 1791459711, cert-manager/cert-manager-istio-csr-rhel9 1791459759, cert-manager/cert-manager-operator-bundle 1791966259, cert-manager/jetstack-cert-manager-acmesolver-rhel9 1791459707
    fixed: vendor fix RHSA-2026:82354
  • Red Hat Cert Manager support for Red Hat OpenShift release 1.20 cert-manager/cert-manager-trust-manager-rhel9 1790598593
    fixed: vendor fix RHSA-2026:72502
  • Red Hat Discovery 2 discovery/discovery-ui-rhel9 1782166952, discovery/discovery-server-rhel9 1782159791
    fixed: vendor fix RHSA-2026:29197
  • Red Hat Enterprise Linux AppStream (v. 9) openssl-perl 3.5.5-4.el9_8
    fixed: vendor fix RHSA-2026:25239
  • Red Hat Enterprise Linux AppStream (v. 10) openssl-perl 3.5.5-4.el10_2
    fixed: vendor fix RHSA-2026:25237
  • Red Hat Enterprise Linux BaseOS (v. 9) openssl 3.5.5-4.el9_8, openssl-libs 3.5.5-4.el9_8
    fixed: vendor fix RHSA-2026:25239
show 5 more
  • Red Hat Enterprise Linux BaseOS (v. 10) openssl 3.5.5-4.el10_2, openssl-libs 3.5.5-4.el10_2
    fixed: vendor fix RHSA-2026:25237
  • Red Hat Hardened Images bootupd 0.3.2-1.hum1, chunkah 0.6.0-3.hum1, openssl 3.5.8-0.1.hum1, openssl3 3.5.8-0.1.hum1, ruby4.0 4.0.6-37.3.hum1, ruby3.3 3.3.10-23.6.hum1, +20 more
    fixed: vendor fix RHSA-2026:67551
  • Red Hat Insights proxy 1.5 insights-proxy/insights-proxy-container-rhel9 1782890503
    fixed: vendor fix RHSA-2026:34102
  • Red Hat Update Infrastructure 5 rhui5/cds-rhel9 1781525684, rhui5/rhua-rhel9 1781525739, rhui5/haproxy-rhel9 1781525671, rhui5/rhua-tp-rhel9 1787241260, rhui5/installer-rhel9 1781525693, rhui5/installer-tp-rhel9 1787135742, +1 more
    fixed: vendor fix RHSA-2026:58981
  • Red Hat Hardened Images rust, unbound, netavark, openshell, rust-podman-sequoia, rubygem3.3-rbs 3.4.0-23.6.hum1, +50 more Red Hat JBoss Core Services jbcs-httpd24-openssl, jbcs-httpd24-openssl-libs, jbcs-httpd24-openssl-perl, jbcs-openssl-win6-x86_64.zip 3.5.5-SP4 Red Hat JBoss Web Server 6 jws-optional-native-components-win6-x86_64.zip 6.2.4.ER1 Red Hat JBoss Web Server 7 jws-optional-native-components-win6-x86_64.zip 6.2.4.ER1 Red Hat Update Infrastructure 5 rhui5/cds-tp-rhel9 1787241206, rhui5/cds-kubernetes-rhel9 1781525677
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.50% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
CNA 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
OSV 3.1 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
julia AppBundler
>=1.0.0, <1.0.1
1.0.1
julia OpenSSL_jll
>=3.0.8+0, <3.5.7+0
3.5.7+0
julia Openresty_jll
>=1.27.1+0
 no fix listed

Affected products

  • OpenSSL OpenSSL

Classification

Weakness
  • CWE-325 Missing Cryptographic Step
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.