CVE-2026-39882

Description

overview: this report shows that the otlp HTTP exporters (traces/metrics/logs) read the full HTTP response body into an in-memory `bytes.Buffer` without a size cap. this is exploitable for memory exhaustion when the configured collector endpoint is attacker-controlled (or a network attacker can mitm the exporter connection). severity HIGH not claiming: this is a remote dos against every default deployment. claiming: if the exporter sends traces to an untrusted collector endpoint (or over a network segment where mitm is realistic), that endpoint can crash the process via a large response body. callsite (pinned): - exporters/otlp/otlptrace/otlptracehttp/client.go:199 - exporters/otlp/otlptrace/otlptracehttp/client.go:230 - exporters/otlp/otlpmetric/otlpmetrichttp/client.go:170 - exporters/otlp/otlpmetric/otlpmetrichttp/client.go:201 - exporters/otlp/otlplog/otlploghttp/client.go:190 - exporters/otlp/otlplog/otlploghttp/client.go:221 permalinks (pinned): - https://github.com/open-telemetry/opentelemetry-go/blob/248da958375e4dfb4a1105645107be3ef04b1c59/exporters/otlp/otlptrace/otlptracehttp/client.go#L199 - https://github.com/open-telemetry/opentelemetry-go/blob/248da958375e4dfb4a1105645107be3ef04b1c59/exporters/otlp/otlptrace/otlptracehttp/client.go#L230 - https://github.com/open-telemetry/opentelemetry-go/blob/248da958375e4dfb4a1105645107be3ef04b1c59/exporters/otlp/otlpmetric/otlpmetrichttp/client.go#L170 - https://github.com/open-telemetry/opentelemetry-go/blob/248da958375e4dfb4a1105645107be3ef04b1c59/exporters/otlp/otlpmetric/otlpmetrichttp/client.go#L201 - https://github.com/open-telemetry/opentelemetry-go/blob/248da958375e4dfb4a1105645107be3ef04b1c59/exporters/otlp/otlplog/otlploghttp/client.go#L190 - https://github.com/open-telemetry/opentelemetry-go/blob/248da958375e4dfb4a1105645107be3ef04b1c59/exporters/otlp/otlplog/otlploghttp/client.go#L221 root cause: each exporter client reads `resp.Body` using `io.Copy(&respData, resp.Body)` into a `bytes.Buffer` on both success and error paths, with no upper bound. impact: a malicious collector can force large transient heap allocations during export (peak memory scales with attacker-chosen response size) and can potentially crash the instrumented process (oom). affected component: - go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp - go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp - go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploghttp repro (local-only): ```bash unzip poc.zip -d poc cd poc make canonical resp_bytes=33554432 chunk_delay_ms=0 ``` expected output contains: ``` [CALLSITE_HIT]: otlptracehttp.UploadTraces::io.Copy(resp.Body) [PROOF_MARKER]: resp_bytes=33554432 peak_alloc_bytes=118050512 ``` control (same env, patched target): ```bash unzip poc.zip -d poc cd poc make control resp_bytes=33554432 chunk_delay_ms=0 ``` expected control output contains: ``` [CALLSITE_HIT]: otlptracehttp.UploadTraces::io.Copy(resp.Body) [NC_MARKER]: resp_bytes=33554432 peak_alloc_bytes=512232 ``` attachments: poc.zip (attached) [PR_DESCRIPTION.md](https://github.com/user-attachments/files/25564272/PR_DESCRIPTION.md) [attack_scenario.md](https://github.com/user-attachments/files/25564273/attack_scenario.md) [poc.zip](https://github.com/user-attachments/files/25564271/poc.zip) Fixed in: https://github.com/open-telemetry/opentelemetry-go/pull/8108

Priority Score