CVE-2026-81869

OpenTelemetry-Go is the Go implementation of OpenTelemetry. From version 1.10.0 until 1.33.0, the sdk/trace/span.go attribute truncation path can fail to enforce AttributeValueLengthLimit for string and string-slice attributes containing the valid Unicode replacement character U+FFFD. safeTruncateValidUTF8 treats the valid replacement rune as invalid UTF-8 and returns the original input, while strings.ToValidUTF8 leaves that valid rune unchanged, so a second safeTruncate attempt can also return the oversized value. An attacker who controls span attribute content can retain values longer than the configured limit, increasing per-span memory use and weakening denial-of-service protection in the instrumented process. This issue is fixed in version 1.33.0.

• https://github.com/open-telemetry/opentelemetry-go/commit/e016a78c9f5b24a1c2beeaad47686c2f2213f49a
• https://github.com/open-telemetry/opentelemetry-go/issues/5996
• https://github.com/open-telemetry/opentelemetry-go/pull/5997
• https://github.com/open-telemetry/opentelemetry-go/releases/tag/sdk/v1.33.0
• https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-p9f8-wvj8-2fg8
• https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-p9f8-wvj8-2fg8