Description
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, in cases where UDP DNS filter is configured with local resolution containing a name with the length of 255 octets or remote resolution for a name of 255 octets long can complete successfully, a query with such name will result in abnormal process termination. The abnormal process termination is triggered by an invalid runtime precondition that the query name is strictly less than 255 octets, contradicting DNS specification rfc1035#section-2.3.4 that the name can be 255 or less octets. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.
Published: 2026-06-26
Score: 5.9 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

The flaw in Envoy’s DNS UDP filter triggers abnormal process termination when a DNS query with a name length of 255 octets succeeds. The runtime check incorrectly requires the name to be strictly shorter than 255 octets, violating the DNS specification. This defect falls under CWE‑480 and results in the proxy process crashing, which effectively denies service to clients that rely on the affected proxy configuration.

Affected Systems

The vulnerability applies to envoyproxy envoy versions earlier than 1.35.11, 1.36.7, 1.37.3, and 1.38.1. Any instance of Envoy running a pre‑patch version and configured with the UDP DNS filter for either local or remote resolution of a 255‑octet name is at risk. Upgrading to one of the specified patch releases eliminates the issue.

Risk and Exploitability

The CVSS score of 5.9 indicates moderate severity. Because no authentication or additional privileges are required, an attacker with the ability to send DNS UDP packets to the Envoy service can trigger the crash. The EPSS score is currently undefined, and the vulnerability is not listed in the CISA KEV catalog, suggesting a lower but still present risk profile. In practice, exploitation would rely on crafting a DNS query with a maximum‑length name, which is feasible over the network layer.

Generated by OpenCVE AI on June 26, 2026 at 19:52 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade Envoy to version 1.35.11 or newer (including 1.36.7, 1.37.3, or 1.38.1).
  • If an upgrade cannot be performed immediately, restrict DNS queries to the Envoy proxy by configuring firewall or ACL rules to block UDP packets containing 255‑octet names or implement DNS name length validation in the proxy’s DNS filter.
  • If UDP DNS filtering is not required for a given environment, consider disabling the DNS UDP filter altogether to eliminate the risk.

Generated by OpenCVE AI on June 26, 2026 at 19:52 UTC.

Tracking

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Advisories

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History

Fri, 26 Jun 2026 23:00:00 +0000

Type Values Removed Values Added
First Time appeared Envoyproxy
Envoyproxy envoy
Vendors & Products Envoyproxy
Envoyproxy envoy

Fri, 26 Jun 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Fri, 26 Jun 2026 18:15:00 +0000

Type Values Removed Values Added
Description 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, in cases where UDP DNS filter is configured with local resolution containing a name with the length of 255 octets or remote resolution for a name of 255 octets long can complete successfully, a query with such name will result in abnormal process termination. The abnormal process termination is triggered by an invalid runtime precondition that the query name is strictly less than 255 octets, contradicting DNS specification rfc1035#section-2.3.4 that the name can be 255 or less octets. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.
Title Envoy: Abnormal process termination in DNS UDP filter
Weaknesses CWE-480
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Subscriptions

Envoyproxy Envoy
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-26T18:32:51.626Z

Reserved: 2026-05-21T15:33:08.292Z

Link: CVE-2026-48497

cve-icon Vulnrichment

Updated: 2026-06-26T18:32:47.045Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-26T22:45:05Z

Weaknesses
  • CWE-480

    Use of Incorrect Operator