CVE-2026-26309
published 2026-03-10CVE-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()…
PriorityP428medium5.3CVSS 3.1
AVNACLPRNUINSUCNINAL
EPSS
0.36%
28.4th percentile
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.
Affected
10 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| envoyproxy | envoy | < 1.34.13 | 1.34.13 |
| envoyproxy | envoy | — | — |
| envoyproxy | envoy | — | — |
| envoyproxy | envoy | — | — |
| envoyproxy | envoy | — | — |
| envoyproxy | envoy | >= 1.35.0 < 1.35.8 | 1.35.8 |
| envoyproxy | envoy | >= 1.36.0 < 1.36.5 | 1.36.5 |
| github.com | envoyproxy_envoy | 0 – 1.34.12 | — |
| github.com | envoyproxy_envoy | 1.35.0 – 1.35.8 | — |
| github.com | envoyproxy_envoy | 1.36.0 – 1.36.4 | — |
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GHSA
Envoy affected by off-by-one write in JsonEscaper::escapeString()
ghsa·2026-03-10
CVE-2026-26309 [MEDIUM] CWE-193 Envoy affected by off-by-one write in JsonEscaper::escapeString()
Envoy affected by off-by-one write in JsonEscaper::escapeString()
### Summary
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.
### Details
The bug is in the control-character escaping path in source/common/common/
json_escape_string.h:67.
- The function pre-sizes result to the final length: std::string
result(input.size() + required_size, '\\');
- For control characters (0x00..0x1f), it emits a JSON escape sequence of
length 6: \u00XX.
- It uses sprintf(&result[position + 1], "u%04x", ...), which writes 5 chars +
a trailing NUL (\0) starting at result[position + 1].
- Then it does position += 6
OSV
Envoy affected by off-by-one write in JsonEscaper::escapeString()
osv·2026-03-10
CVE-2026-26309 [MEDIUM] Envoy affected by off-by-one write in JsonEscaper::escapeString()
Envoy affected by off-by-one write in JsonEscaper::escapeString()
### Summary
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.
### Details
The bug is in the control-character escaping path in source/common/common/
json_escape_string.h:67.
- The function pre-sizes result to the final length: std::string
result(input.size() + required_size, '\\');
- For control characters (0x00..0x1f), it emits a JSON escape sequence of
length 6: \u00XX.
- It uses sprintf(&result[position + 1], "u%04x", ...), which writes 5 chars +
a trailing NUL (\0) starting at result[position + 1].
- Then it does position += 6
No detection rules found.
No public exploits indexed.
Wiz
CVE-2026-26308 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.5
CVE-2026-26308 [HIGH] CVE-2026-26308 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-26308 :
Envoy vulnerability analysis and mitigation
Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, the Envoy RBAC (Role-Based Access Control) filter contains a logic vulnerability in how it validates HTTP headers when multiple values are present for the same header name. Instead of validating each header value individually, Envoy concatenates all values into a single comma-separated string. This behavior allows attackers to bypass RBAC policies—specifically "Deny" rules—by sending duplicate headers, effectively obscuring the malicious value from exact-match mechanisms. This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.
Source : NVD
## 8.2
Score
Published March 10, 2026
Severity HIGH
CNA Score 7.5
Wiz
CVE-2026-26310 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.5
CVE-2026-26310 [HIGH] CVE-2026-26310 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-26310 :
Envoy vulnerability analysis and mitigation
Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, calling Utility::getAddressWithPort with a scoped IPv6 addresses causes a crash. This utility is called in the data plane from the original_src filter and the dns filter. This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.
Source : NVD
## 7.5
Score
Published March 10, 2026
Severity HIGH
CNA Score 5.9
Affected Technologies
Envoy
Amazon Linux
Has Public Exploit Yes
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 0.5
Exploitation Probability (EPSS) N/A
Affected packages and libraries
github.com/envoyproxy/envoy
envoy
Sources
Wiz
CVE-2026-26311 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 5.9
CVE-2026-26311 [MEDIUM] CVE-2026-26311 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-26311 :
Envoy vulnerability analysis and mitigation
Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, a logic vulnerability in Envoy's HTTP connection manager (FilterManager) that allows for Zombie Stream Filter Execution. This issue creates a "Use-After-Free" (UAF) or state-corruption window where filter callbacks are invoked on an HTTP stream that has already been logically reset and cleaned up. The vulnerability resides in source/common/http/filter_manager.cc within the FilterManager::decodeData method. The ActiveStream object remains valid in memory during the deferred deletion window. If a DATA frame arrives on this stream immediately after the reset (e.g., in the same packet processing cycle), the HTTP/2 codec invokes A
Wiz
CVE-2026-26309 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.5
CVE-2026-26309 [HIGH] CVE-2026-26309 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-26309 :
Envoy vulnerability analysis and mitigation
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.
Source : NVD
## 5.3
Score
Published March 10, 2026
Severity MEDIUM
CNA Score 5.3
Affected Technologies
Envoy
Amazon Linux
Has Public Exploit Yes
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 0.1
Exploitation Probability (EPSS) N/A
Affe
Wiz
CVE-2026-26330 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.5
CVE-2026-26330 [HIGH] CVE-2026-26330 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-26330 :
Envoy vulnerability analysis and mitigation
Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, At the rate limit filter, if the response phase limit with apply_on_stream_done in the rate limit configuration is enabled and the response phase limit request fails directly, it may crash Envoy. When both the request phase limit and response phase limit are enabled, the safe gRPC client instance will be re-used for both the request phase request and response phase request. But after the request phase request is done, the inner state of the request phase limit request in gRPC client is not cleaned up. When a second limit request is sent at response phase, and the second limit request fails directly, the previous request's inn
2026-03-10
Published