Is CVE-2026-26309 actively exploited?

CVE-2026-26309 has no public evidence of in-the-wild exploitation as of 2026-03-11.

What is the CVSS score for CVE-2026-26309?

CVE-2026-26309 has a CVSS score of 5.3 (MEDIUM severity). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

How do I patch CVE-2026-26309?

Patch guidance is available from envoyproxy security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2026-26309.

CVE-2026-26309 - remediation guidance & executive summary

Q: Which products are affected by CVE-2026-26309?

4 products: envoyproxy envoy, envoyproxy envoy, envoyproxy envoy, envoyproxy envoy.

Description

Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, an off-by-one write in Envoy::JsonEscaper::escapeString() can corrupt std::string null-termination, causing undefined behavior and potentially leading to crashes or out-of-bounds reads when the resulting string is later treated as a C-string. This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.

CVSS Metrics

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack Vector: network
Complexity: low
Privileges: none
User Action: none
Scope: unchanged
Confidentiality: none
Integrity: none
Availability: low
Weaknesses: CWE-193

Metadata

Primary Vendor: ENVOYPROXY
Published: 3/10/2026
Last Modified: 3/11/2026
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

Affected Products

envoyproxy : envoyenvoyproxy : envoyenvoyproxy : envoyenvoyproxy : envoy

Remediation Guidance

Executive Summary

Cite this page

CVE-2026-26309. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2026-26309

View on NIST NVD

CVE-2026-26309 vulnerability