---
id: "CVE-2026-116694"
kind: "vulnerability"
aliases: ["CVE-2026-116694", "GHSA-f5m9-jfrj-jjj7"]
title: "OpenTelemetry Python: Unbounded memory allocation in Jaeger baggage propagation"
severity: "medium"
cvss: 6.3
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "opentelemetry-propagator-jaeger", "fixed": ["1.45.0"], "affected": "<= 1.44.0", "ecosystem": "pypi"}]
ecosystems: ["pypi"]
tags: ["cwe-770", "microservices", "opentelemetry", "package", "python", "self-hosted"]
not_affected_if: ["default-config", "header-limits-enforced", "propagator-not-installed"]
published_at: "2026-10-27T21:06:54+00:00"
first_seen_at: "2026-10-27T21:09:20+00:00"
updated_at: "2026-10-27T21:29:21+00:00"
sources: [{"source": "ghsa", "url": "https://github.com/advisories/GHSA-f5m9-jfrj-jjj7", "first_seen_at": "2026-10-27T21:09:20+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-116694", "first_seen_at": "2026-10-27T21:29:21+00:00"}]
---

# OpenTelemetry Python: Unbounded memory allocation in Jaeger baggage propagation

The Jaeger propagator in opentelemetry-propagator-jaeger did not limit how many inbound uberctx-* baggage headers it parsed. An attacker can send oversized baggage to cause extra CPU work and short-lived memory allocation, which can degrade availability.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- pypi:opentelemetry-propagator-jaeger affected <= 1.44.0 fixed 1.45.0

## How to check

- Run `pip show opentelemetry-propagator-jaeger` and check whether the version is `1.44.0` or earlier.
- Search the codebase for `JaegerPropagator` or `opentelemetry.propagators.jaeger` to see whether the propagator is enabled.

## Fix

- Upgrade `opentelemetry-propagator-jaeger` to `1.45.0` or later, for example `pip install --upgrade opentelemetry-propagator-jaeger>=1.45.0`.

## Timeline

- 2026-10-27T21:09:20+00:00 ghsa https://github.com/advisories/GHSA-f5m9-jfrj-jjj7
- 2026-10-27T21:29:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-116694

## From the sources

## Summary

`JaegerPropagator.extract()` in `opentelemetry-propagator-jaeger` did not enforce limits when extracting inbound `uberctx-*` baggage headers. Attacker-controlled baggage could cause unnecessary CPU work and short-lived heap allocations while processing more data than the propagator should accept.

## Impact

Services that enable the optional Jaeger propagator and accept untrusted inbound propagation headers may experience increased per-request resource usage. This can contribute to denial-of-service risk when transport-level limits are absent or configured above the baggage limits.

The practical impact for most Python web deployments is limited. The package must be installed separately, and the Jaeger propagator is not enabled by the default OpenTelemetry Python configuration.

Common Python web servers also constrain request headers before they reach the propagator:

- Gunicorn allows a maximum of 100 request-header fields and 8,190 bytes per field by default.
- Uvicorn’s h11 implementation limits its incomplete-event buffer to 16,384 bytes by default.

The risk is higher for non-HTTP transports, custom `TextMapGetter` implementations, or deployments where server and gateway limits have been increased or disabled.

The impact is limited to availability. This issue does not expose or modify telemetry data and does not allow code execution.

## Patches

Versions of `opentelemetry-propagator-jaeger` earlier than `1.45.0` are affected.

Upgrade `opentelemetry-propagator-jaeger` to version `1.45.0` or later.

Version `1.45.0` limits extraction to 180 entries and 8,192 total bytes and skips entries larger than 4,096 bytes.

## Credit

tonghuaroot

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_