Skip to content
VulniPulse
Sign in
Advisory severityMedium4.4Red Hat Linux

Medium [CVE-2026-47778] Information disclosure via malicious certificate with NUL byte in DNS Subject Alternative Name (SAN)

This medium-severity Red Hat Linux advisory covers CVE-2026-47778 affecting OpenShift Service Mesh 2, OpenShift Service Mesh 3.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-47778 Source published Source updated

VulniPulse record published Record updated

CVE-2026-47778
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

Summary

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a structural flaw was identified in DefaultCertValidator::verifySubjectAltName where the extracted DNS SAN string is cast to a C-style string using.c_str() before being passed to the Utility::dnsNameMatch() algorithm.

If the attacker serves a certificate with a dNSName SAN containing an embedded NUL byte, the helper Utility::generalNameAsString captures the complete string including the NUL. However, when.c_str() evaluates it, implicit conversion to absl::string_view inside dnsNameMatch relies on strlen(), prematurely truncating the evaluation context.

Envoy evaluates trucated string against the exact required config_san match and returns true, thereby successfully validating the string with the Nul byte for an upstream routing. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.

A remote attacker could exploit a structural flaw in the DefaultCertValidator::verifySubjectAltName function by presenting a specially crafted certificate. This certificate would contain a NUL byte within its DNS Subject Alternative Name (SAN) field.

Due to incorrect string handling, Envoy would prematurely truncate the DNS SAN string during validation, allowing the malicious certificate to be accepted for upstream routing.

Is CVE-2026-47778 exploited?

No exploitation is reported in the sources VulniPulse tracks: CVE-2026-47778 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.

How do I fix CVE-2026-47778?

Upgrade to a fixed release named by Red Hat:

  • 1.35.11
  • 1.36.7
  • 1.37.3
  • 1.38.1

Confirm against the vendor advisory before you patch.

Affected versions
  • < 1.35.11
  • < 1.36.7
  • < 1.37.3
  • < 1.38.1

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

Fixed versions
  • 1.35.11
  • 1.36.7
  • 1.37.3
  • 1.38.1

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation
  • 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 14 days ago·verify at source

Get an email when Red Hat publishes the next one.

See Red Hat's last 90 days of advisories first. Then choose one product with live alerts free for life, or a free month of real-time alerts on everything with the severity, the fixed version and the vendor's link (card needed, then US$15/month; we email you before the first charge).

Alert me about Red Hat

More Red Hat Linux advisories

All Red Hat Linux advisories

iPhone and Android apps · New on the App Store

Monitor future Red Hat Linux CVEs from your phone.

Choose a whole vendor or a precise platform, then receive matching security advisories by phone notification, email, or both. Coverage follows 34 official vendor sources and 160+ reviewed platform categories.

Download on the App StoreGet CVE alerts on AndroidSee app features

Discussion(0)

No comments yet. Share field notes, upgrade gotchas, or questions — verify against the vendor advisory before acting on community advice.

Sign in to join the discussion.