CVE-2026-26309
Off-by-One Write in Envoy JsonEscaper Causes Crashes
Publication date: 2026-03-10
Last updated on: 2026-03-11
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| envoyproxy | envoy | to 1.34.13 (exc) |
| envoyproxy | envoy | From 1.35.0 (inc) to 1.35.8 (exc) |
| envoyproxy | envoy | From 1.36.0 (inc) to 1.36.5 (exc) |
| envoyproxy | envoy | 1.37.0 |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-193 | A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability is an off-by-one write error in the Envoy proxy's JsonEscaper::escapeString() function. It can corrupt the null-termination of a std::string, which may cause undefined behavior. Specifically, when the corrupted string is later used as a C-string, it can lead to crashes or out-of-bounds reads.
How can this vulnerability impact me? :
The vulnerability can cause the Envoy proxy to crash or behave unpredictably due to out-of-bounds reads. This can lead to denial of service or instability in systems relying on Envoy for edge, middle, or service proxy functions.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, you should upgrade Envoy to one of the fixed versions: 1.37.1, 1.36.5, 1.35.8, or 1.34.13.