CVE-2026-116693: ReDoS — HIGH

CISO Take

dd-trace, the Datadog APM client for Node.js, ships a default query-string obfuscation regular expression that backtracks catastrophically on crafted URLs (CWE-1333). The regex runs synchronously on the Node.js event loop, so a single unauthenticated HTTP request can pin the CPU and make the instrumented service unavailable. The blast radius is wide because tracing libraries sit in front of nearly every request path, including AI inference gateways and agent backends. No CVSS score, EPSS data, KEV listing, public exploit or scanner template exists yet, so the likelihood of active exploitation is currently low, but exploitation needs only a long crafted query string. Upgrade dd-trace to 5.131.1 or 6.20.1, and until then consider overriding DD_TRACE_OBFUSCATION_QUERY_STRING_REGEXP with a safe pattern or capping query string length at the proxy or WAF.

Sources:NVDGitHub AdvisoryATLAS

What is the risk?

Moderate risk. Exploitation is remote and unauthenticated, requires no user interaction, and has availability impact only; there is no confidentiality or integrity impact. Severity and EPSS are not yet scored, and no public exploit, Nuclei template or KEV listing exists. Exposure depends on whether dd-trace is loaded in internet-facing Node.js services. Because the event loop is blocked, one request can stall all concurrent requests on that process, so the effective impact on an affected service is high.

How does the attack unfold?

Initial Access

The attacker sends an unauthenticated HTTP request with a crafted long query string to a public Node.js endpoint.

AML.T0049

Exploitation

The dd-trace obfuscation regex backtracks excessively while the tracer records URL metadata on the event loop.

Impact

CPU saturation blocks request processing and takes the AI-serving application offline.

AML.T0029

Initial Access

The attacker sends an unauthenticated HTTP request with a crafted long query string to a public Node.js endpoint.

AML.T0049

Exploitation

The dd-trace obfuscation regex backtracks excessively while the tracer records URL metadata on the event loop.

Impact

CPU saturation blocks request processing and takes the AI-serving application offline.

AML.T0029

How severe is it?

CVSS 3.1

N/A

EPSS

0.4%

chance of exploitation in 30 days

Higher than 39% of all CVEs

Source: EPSS v3 — FIRST.org

Exploitation Status

No known exploitation

Sophistication

Trivial

What should I do?

1 step

1) Upgrade dd-trace to 5.131.1 or 6.20.1 or later across all Node.js services, including transitive and containerized deployments. 2) As a temporary workaround, set DD_TRACE_OBFUSCATION_QUERY_STRING_REGEXP to a simplified, non-backtracking pattern, or disable query string reporting. 3) Enforce a maximum URL and query string length at the reverse proxy, API gateway or WAF. 4) Detect with alerts on sustained single-core CPU saturation, event loop lag spikes and health check timeouts correlated with unusually long query strings in access logs. 5) Inventory dd-trace versions with SBOM or npm ls scans.

How is it classified?

DoSAPIFrameworkAML.T0029- Denial of AI Service AML.T0049- Exploit Public-Facing Application

Which compliance frameworks are affected?

This CVE is relevant to:

ISO 42001

A.6.2.6-AI system operation and monitoring

NIST AI RMF

MANAGE 2.3-Response to risks and unknown risks

OWASP LLM Top 10

LLM10-Unbounded Consumption

Frequently Asked Questions

What is CVE-2026-116693?

dd-trace, the Datadog APM client for Node.js, ships a default query-string obfuscation regular expression that backtracks catastrophically on crafted URLs (CWE-1333). The regex runs synchronously on the Node.js event loop, so a single unauthenticated HTTP request can pin the CPU and make the instrumented service unavailable. The blast radius is wide because tracing libraries sit in front of nearly every request path, including AI inference gateways and agent backends. No CVSS score, EPSS data, KEV listing, public exploit or scanner template exists yet, so the likelihood of active exploitation is currently low, but exploitation needs only a long crafted query string. Upgrade dd-trace to 5.131.1 or 6.20.1, and until then consider overriding DD_TRACE_OBFUSCATION_QUERY_STRING_REGEXP with a safe pattern or capping query string length at the proxy or WAF.

Is CVE-2026-116693 actively exploited?

No confirmed active exploitation of CVE-2026-116693 has been reported, but organizations should still patch proactively.

How to fix CVE-2026-116693?

1) Upgrade dd-trace to 5.131.1 or 6.20.1 or later across all Node.js services, including transitive and containerized deployments. 2) As a temporary workaround, set DD_TRACE_OBFUSCATION_QUERY_STRING_REGEXP to a simplified, non-backtracking pattern, or disable query string reporting. 3) Enforce a maximum URL and query string length at the reverse proxy, API gateway or WAF. 4) Detect with alerts on sustained single-core CPU saturation, event loop lag spikes and health check timeouts correlated with unusually long query strings in access logs. 5) Inventory dd-trace versions with SBOM or npm ls scans.

What systems are affected by CVE-2026-116693?

This vulnerability affects the following AI/ML architecture patterns: Model serving, Agent frameworks, LLM API gateways, RAG pipelines, MCP servers.

What is the CVSS score for CVE-2026-116693?

No CVSS score has been assigned yet.

What is the AI security impact?

Affected AI Architectures

Model servingAgent frameworksLLM API gatewaysRAG pipelinesMCP servers

MITRE ATLAS Techniques

AML.T0029Denial of AI Service

AML.T0049Exploit Public-Facing Application

Compliance Controls Affected

ISO 42001: A.6.2.6

NIST AI RMF: MANAGE 2.3

OWASP LLM Top 10: LLM10

What are the technical details?

Original Advisory

dd-trace is the Datadog APM client for Node.js. From 2.0.0 until 5.131.1 and 6.20.1, the default DD_TRACE_OBFUSCATION_QUERY_STRING_REGEXP can perform excessive backtracking on attacker-controlled URL query strings. The expression is applied synchronously while recording HTTP URL metadata, allowing a crafted request to consume excessive CPU, stall request processing, and make the instrumented application unavailable. This issue is fixed in versions 5.131.1 and 6.20.1.

Exploitation Scenario

An attacker finds a public Node.js endpoint that fronts an LLM or agent service instrumented with dd-trace. They send a request with a long query string built to trigger catastrophic backtracking in the default obfuscation regex. The tracer evaluates the regex synchronously while recording HTTP URL metadata, blocking the event loop. The attacker repeats the request at low volume to keep the service unresponsive, which disrupts inference, agent workflows and monitoring health checks.

Weaknesses (CWE)

CWE-1333Inefficient Regular Expression ComplexityPrimary CWE-1333Inefficient Regular Expression Complexity

CWE-1333 — Inefficient Regular Expression Complexity: The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.

[Architecture and Design] Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
[System Configuration] Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.

Source: MITRE CWE corpus.