CVE-2026-54285

Overview

W3CBaggagePropagator.extract() in @opentelemetry/core does not enforce size limits when parsing inbound baggage HTTP headers. The W3C Baggage specification recommends a maximum of 8,192 bytes and 180 entries; these limits were only enforced on the outbound (inject()) path, not on the inbound (extract()) path. Parsing oversized baggage causes memory allocation proportional to the header size without any cap.

Workarounds

Ensure header size limits are configured at the server or gateway level. The default Node.js HTTP header limit (16 KB) mitigates external attack vectors independently of this fix. For non-HTTP transports receiving baggage from untrusted sources, validate input size before passing it to the propagator.

References

• W3C Baggage Specification - Limits
• opentelemetry-java: GHSA-rcgg-9c38-7xpx
• opentelemetry-go: GHSA-mh2q-q3fh-2475

Credit

Reported by tonghuaroot.

The practical availability impact for most Node.js deployments is limited. Node.js enforces a default --max-http-header-size of 16,384 bytes on the total combined size of all HTTP headers, constraining what an external attacker can deliver before the propagator is reached. Additionally, the header is already in memory (parsed by the HTTP layer) by the time it reaches the propagator - the additional allocation is the overhead of splitting into entry objects, not an unbounded read.

The risk is higher when transport-layer limits are absent - e.g., non-HTTP transports (messaging systems, custom TextMapGetter implementations) or deployments that have raised --max-http-header-size.

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

CVE-2026-54285 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.8.0); upgrading removes the vulnerable code path.

Kodem intelligence

Update @opentelemetry/core to version 2.8.0 or later. The fix enforces limits consistent with the W3C Baggage specification at the propagator level:

• Maximum total baggage size: 8,192 bytes
• Maximum number of entries: 180
• Maximum per-entry size: 4,096 bytes

Headers that exceed these limits are truncated at the point the limit is reached.

1. What is CVE-2026-54285? CVE-2026-54285 is a medium-severity allocation of resources without limits or throttling vulnerability in @opentelemetry/core (npm), affecting versions < 2.8.0. It is fixed in 2.8.0. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. How severe is CVE-2026-54285? CVE-2026-54285 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @opentelemetry/core are affected by CVE-2026-54285? @opentelemetry/core (npm) versions < 2.8.0 is affected.
4. Is there a fix for CVE-2026-54285? Yes. CVE-2026-54285 is fixed in 2.8.0. Upgrade to this version or later.
5. Is CVE-2026-54285 exploitable, and should I be worried? Whether CVE-2026-54285 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-54285 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-54285? Upgrade @opentelemetry/core to 2.8.0 or later.