Vulnerability Advisory : opentelemetry-go: AttributeValueLengthLimit is fully bypassed by attribute values composed of valid U+FFFD runes with LOW Attack Complexity

OpenTelemetry-Go is the Go implementation of OpenTelemetry. From SDK version 1.33.0, SDK log version 0.9.0, and trace version 1.35.0 until version 1.47.0, the AttributeValueLengthLimit and WithAttributeValueLengthLimit truncation paths in sdk/internal/attrnorm, sdk/log/internal/attrnorm, and trace/auto.go do not count valid U+FFFD replacement characters. This is a distinct incomplete-fix defect in the replacement truncation code introduced by the remediation for CVE-2026-81869. Values composed of or dominated by those characters can therefore exceed the configured character and memory bound in span, log-record, and auto-instrumentation trace attributes. Attacker-controlled telemetry attributes can increase retained memory and pipeline pressure, while confidentiality and integrity are not affected. This issue is fixed in version 1.47.0.