Improper input validation in Swift-Otel Swift-W3c-Trace-Context

CVE-2026-23886

Swift W3C TraceContext is a Swift implementation of the W3C Trace Context standard, and Swift OTel is an OpenTelemetry Protocol (OTLP) backend for Swift Log, Swift Metrics, and Swift Distributed Tracing. Prior to Swift W3C TraceContext version 1.0.0-beta.5 and Swift OTel version 1.0.4, a denial-of-service vulnerability due to improper input validation allows a remote attacker to crash the service via a malformed HTTP header. This allows crashing the process with data coming from the network when used with, for example, an HTTP server. Most common way of using Swift W3C Trace Context is through Swift OTel. Version 1.0.0-beta.5 of Swift W3C TraceContext and version 1.0.4 of Swift OTel contain a patch for this issue. As a workaround, disable either Swift OTel or the code that extracts the trace information from an incoming header (such as a `TracingMiddleware`).

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

EPSS exploit prediction

EPSS: 0.005 (37.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 37.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-23886: held from 0.004 to 0.005.

EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-23886?
CVE-2026-23886 is a medium-severity vulnerability in Swift-Otel Swift-W3c-Trace-Context, classified under Improper Input Validation. CVSS score: 5.3/10. Published 2026-01-19.
How severe is CVE-2026-23886?
Medium severity. CVSS v3 base score is 5.3 out of 10.