CVE-2026-126360
What it is
OpenTelemetry Python provides the Python API and SDK for OpenTelemetry. Prior to 1.45.2, TraceContextTextMapPropagator.extract() in opentelemetry-api can perform quadratic-time regular-expression backtracking on a malformed traceparent value containing a trace-context prefix, a long whitespace sequence, and an embedded newline. Exploitation requires an attacker-controlled carrier that preserves embedded newlines and permits a sufficiently large value, because conforming HTTP header values cannot contain embedded newlines. JSON-based carriers, including applicable MCP request metadata integrations, can preserve the required newline depending on the SDK, instrumentation, and message-size limits. Parsing on an asynchronous server's event-loop thread can consume excessive CPU and delay unrelated requests, while the advisory does not establish disclosure, modification, or code execution. This issue is fixed in version 1.45.2.
At a glance
- Exploitability
- Can be exploited over the network without logging in. Limited direct impact.
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- ReservedThe CVE id was reserved by its CNA
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: not scored yet.
- Severity: 5.3 MEDIUM (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Weakness
- CWE-1333
- Record status
- Received
Attack profile CVSS 3.1 · 5.3
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-126360.md and follow it. Check whether this project is affected by CVE-2026-126360. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://github.com/open-telemetry/opentelemetry-python/commit/78123a2755c907c602e02352aebed4be86aa5350
- https://github.com/open-telemetry/opentelemetry-python/commit/faa72dae511ae64a7bf8ca63eff9ad4387d0b939
- https://github.com/open-telemetry/opentelemetry-python/pull/5818
- https://github.com/open-telemetry/opentelemetry-python/pull/5856
- https://github.com/open-telemetry/opentelemetry-python/releases/tag/v1.45.2
- https://github.com/open-telemetry/opentelemetry-python/security/advisories/GHSA-mf5v-w3w3-f6cg
References
- https://github.com/open-telemetry/opentelemetry-python/commit/78123a2755c907c602e02352aebed4be86aa5350
- https://github.com/open-telemetry/opentelemetry-python/commit/faa72dae511ae64a7bf8ca63eff9ad4387d0b939
- https://github.com/open-telemetry/opentelemetry-python/pull/5818
- https://github.com/open-telemetry/opentelemetry-python/pull/5856
- https://github.com/open-telemetry/opentelemetry-python/releases/tag/v1.45.2
- https://github.com/open-telemetry/opentelemetry-python/security/advisories/GHSA-mf5v-w3w3-f6cg