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Swift W3C TraceContext vulnerable to a malformed HTTP header causing a crash

Moderate severity GitHub Reviewed Published Jan 19, 2026 in swift-otel/swift-w3c-trace-context • Updated Jan 21, 2026

Package

swift github.com/swift-otel/swift-otel (Swift)

Affected versions

< 1.0.4

Patched versions

1.0.4
swift github.com/swift-otel/swift-w3c-trace-context (Swift)
< 1.0.0-beta.5
1.0.0-beta.5

Description

Impact

A denial-of-service vulnerability due to improper input validation allows a remote attacker to crash the service via a malformed HTTP header.

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.

Patches

swift-otel/swift-w3c-trace-context@5da9b14

Workarounds

Disable either Swift OTel or the code that extracts the trace information from an incoming header (such as a TracingMiddleware).

References

Swift W3C TraceContext 1.0.0-beta.5
Swift OTel 1.0.4

References

@slashmo slashmo published to swift-otel/swift-w3c-trace-context Jan 19, 2026
Published by the National Vulnerability Database Jan 19, 2026
Published to the GitHub Advisory Database Jan 21, 2026
Reviewed Jan 21, 2026
Last updated Jan 21, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(31st percentile)

Weaknesses

Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Learn more on MITRE.

CVE ID

CVE-2026-23886

GHSA ID

GHSA-mvpq-2v8x-ww6g

Source code

Credits

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