CVE-2026-26309: Envoy affected by off-by-one write in JsonEscaper::escapeString()

March 10, 2026

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.

References

github.com/advisories/GHSA-56cj-wgg3-x943
github.com/envoyproxy/envoy
github.com/envoyproxy/envoy/security/advisories/GHSA-56cj-wgg3-x943
nvd.nist.gov/vuln/detail/CVE-2026-26309

Code Behaviors & Features

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