Medium [CVE-2026-42505] Go crypto/tls: Information disclosure in Encrypted Client Hello
This medium-severity Red Hat Linux advisory covers CVE-2026-42505 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
Handshakes which used Encrypted Client Hello could be de-anonymized by a passive network observer due to a disclosure of pre-shared key identities in the unencrypted client hello. A flaw was found in the `crypto/tls` package in Go.
The vulnerability stems from the unintentional exposure of pre-shared key identities within the unencrypted client hello, potentially enabling an attacker to link previously anonymous connections. This primarily affects the privacy of communications rather than integrity or availability.
Red Hat severity: Moderate — CVSS 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N). Weakness: CWE-201.
Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat Hardened Images; and 41 more.
Affected products named by the advisory: Red Hat OpenShift distributed tracing 3.10.1; Assisted Installer for Red Hat OpenShift Container Platform 2; cert-manager Operator for Red Hat OpenShift; Compliance Operator; and 37 more.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 24 hours ago·verify at source
- golang-0:1.26.5-1.el10_2
- go-toolset:rhel8-8100020260710105056.a3795dee
- golang-0:1.26.5-1.el9_8
- golang1-26-main-1.26.5-0.1.hum1
- golang1-25-main-1.25.12-0.1.hum1
- rhosdt/opentelemetry-collector-rhel9:1786637598
- rhosdt/opentelemetry-rhel9-operator:1786635175
- RHSA-2026:37436
- RHSA-2026:38995
- RHSA-2026:37435
- RHSA-2026:36477
- RHSA-2026:36510
- RHSA-2026:54773
Official advisory · high-confidence parse· fetched 24 hours ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official advisory · high-confidence parse· fetched 24 hours ago·verify at source
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