CVE-2026-26309

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 v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
https://github.com/envoyproxy/envoy/security/advisories/GHSA-56cj-wgg3-x943	Vendor Advisory Exploit

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:envoyproxy:envoy::::::::
	cpe:2.3:a:envoyproxy:envoy::::::::
	cpe:2.3:a:envoyproxy:envoy::::::::
	cpe:2.3:a:envoyproxy:envoy:1.37.0:::::::*

History

11 Mar 2026, 16:14

Type	Values Removed	Values Added
First Time		Envoyproxy Envoyproxy envoy
References	~~() https://github.com/envoyproxy/envoy/security/advisories/GHSA-56cj-wgg3-x943 -~~	() https://github.com/envoyproxy/envoy/security/advisories/GHSA-56cj-wgg3-x943 - Vendor Advisory, Exploit
CPE		cpe:2.3:a:envoyproxy:envoy:1.37.0:::::::* cpe:2.3:a:envoyproxy:envoy::::::::

11 Mar 2026, 13:53

Type	Values Removed	Values Added
Summary		(es) Envoy es un proxy de borde/intermedio/servicio de alto rendimiento. Antes de 1.37.1, 1.36.5, 1.35.8 y 1.34.13, una escritura por un byte en Envoy::JsonEscaper::escapeString() puede corromper la terminación nula de std::string, causando comportamiento indefinido y potencialmente llevando a fallos o lecturas fuera de límites cuando la cadena resultante es tratada posteriormente como una cadena C. Esta vulnerabilidad está corregida en 1.37.1, 1.36.5, 1.35.8 y 1.34.13.

10 Mar 2026, 20:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-03-10 20:16

Updated : 2026-03-11 16:14

NVD link : CVE-2026-26309

Mitre link : CVE-2026-26309

CVE.ORG link : CVE-2026-26309

JSON object : View

Products Affected

envoyproxy

envoy

CWE

CWE-193

Off-by-one Error

{"id": "CVE-2026-26309", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "LOW", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 1.4, "exploitabilityScore": 3.9}, {"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "LOW", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 1.4, "exploitabilityScore": 3.9}]}, "published": "2026-03-10T20:16:35.880", "references": [{"url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-56cj-wgg3-x943", "tags": ["Vendor Advisory", "Exploit"], "source": "security-advisories@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-193"}]}], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "Envoy es un proxy de borde/intermedio/servicio de alto rendimiento. Antes de 1.37.1, 1.36.5, 1.35.8 y 1.34.13, una escritura por un byte en Envoy::JsonEscaper::escapeString() puede corromper la terminaci\u00f3n nula de std::string, causando comportamiento indefinido y potencialmente llevando a fallos o lecturas fuera de l\u00edmites cuando la cadena resultante es tratada posteriormente como una cadena C. Esta vulnerabilidad est\u00e1 corregida en 1.37.1, 1.36.5, 1.35.8 y 1.34.13."}], "lastModified": "2026-03-11T16:14:20.730", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "C4169052-E37B-4577-8689-4DA8D6AFF3F3", "versionEndExcluding": "1.34.13"}, {"criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "35DB0A9F-BCEA-48D7-97DE-A63FA24B2032", "versionEndExcluding": "1.35.8", "versionStartIncluding": "1.35.0"}, {"criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "B37DDD3B-8F92-4F76-B3B1-F3743CB41339", "versionEndExcluding": "1.36.5", "versionStartIncluding": "1.36.0"}, {"criteria": "cpe:2.3:a:envoyproxy:envoy:1.37.0:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "C5266F62-E0D2-4525-90B6-65921EE14F79"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}