Summary
Datadog dd-trace-py: ReDoS in URL query string obfuscation
A regular expression used to obfuscate URL query strings can consume excessive CPU when processing certain attacker-controlled input. This can stall request processing and cause denial of service in applications using affected HTTP tracing integrations.
Details
The default query-string obfuscation pattern can exhibit excessive backtracking. The pattern is applied synchronously when recording HTTP URL metadata, allowing query-string processing to occupy application resources for an extended period.
As a workaround, set both DD_TRACE_OBFUSCATION_QUERY_STRING_REGEXP and DD_TRACE_OBFUSCATION_QUERY_STRING_PATTERN to the fixed Python-compatible regex below, then restart the application. Setting both variables covers all affected ddtrace versions, including releases before 1.19.0.
export DD_TRACE_OBFUSCATION_QUERY_STRING_REGEXP='(?i)(?:(?:"|%22)?)(?:(?:old[-_]?|new[-_]?)?p(?:ass)?w(?:or)?d(?:1|2)?|pass(?:[-_]?phrase)?|secret|(?:api[-_]?|private[-_]?|public[-_]?|access[-_]?|secret[-_]?|app(?:lication)?[-_]?)key(?:[-_]?id)?|token|consumer[-_]?(?:id|key|secret)|sign(?:ed|ature)?|auth(?:entication|orization)?)(?:(?:\s|%20)*(?:=|%3D)[^&]+|(?:"|%22)(?:\s|%20)*(?::|%3A)(?:\s|%20)*(?:"|%22)(?:%2[^2]|%[^2]|[^"%])+(?:"|%22))|(?:bearer(?:\s|%20)+[a-z0-9._\-]+|token(?::|%3A)[a-z0-9]{13}|gh[opsu]_[0-9a-zA-Z]{36}|(?:(?<![\w-])|(?<=%[0-9a-f]{2}))ey[I-L][\w-]+(?:=|%3D)*\.ey[I-L][\w-]+(?:=|%3D)*(?:\.(?:[\w.+/=-]|%3D|%2F|%2B)+)?|-{5}BEGIN(?:[a-z\s]|%20)+PRIVATE(?:\s|%20)KEY-{5}[^\-]+-{5}END(?:[a-z\s]|%20)+PRIVATE(?:\s|%20)KEY(?:-{5})?(?:\n|%0A)?|(?:ssh-(?:rsa|dss)|ecdsa-[a-z0-9]+-[a-z0-9]+)(?:\s|%20|%09)+(?:[a-z0-9/.+]|%2F|%5C|%2B){100,}(?:=|%3D)*(?:(?:\s|%20|%09)+[a-z0-9._-]+)?)'
export DD_TRACE_OBFUSCATION_QUERY_STRING_PATTERN="$DD_TRACE_OBFUSCATION_QUERY_STRING_REGEXP"
Proof of concept
Detailed triggering inputs and reproduction steps are omitted from this advisory. The patched version includes regression coverage for the affected behavior.
Impact
Regular expression denial of service (ReDoS) affecting applications that process attacker-controlled URL query strings through the vulnerable obfuscation pattern. Successful exploitation can cause excessive CPU consumption, prolonged request latency, and service unavailability.
The vulnerable processing is enabled by default for affected HTTP integrations that include query strings in URL span tags.
A regular expression with worst-case exponential or polynomial matching time is applied to untrusted input, causing excessive CPU use. Typical impact: denial of service when input is crafted to trigger backtracking.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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ddtrace to 3.19.9 or later; ddtrace to 4.15.6 or later
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Frequently Asked Questions
- What is CVE-2026-116588? CVE-2026-116588 is a high-severity inefficient regular expression (ReDoS) vulnerability in ddtrace (pip), affecting versions >= 1.5.0, < 3.19.9. It is fixed in 3.19.9, 4.15.6. A regular expression with worst-case exponential or polynomial matching time is applied to untrusted input, causing excessive CPU use.
- Which versions of ddtrace are affected by CVE-2026-116588? ddtrace (pip) versions >= 1.5.0, < 3.19.9 is affected.
- Is there a fix for CVE-2026-116588? Yes. CVE-2026-116588 is fixed in 3.19.9, 4.15.6. Upgrade to this version or later.
- Is CVE-2026-116588 exploitable, and should I be worried? Whether CVE-2026-116588 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
- What actually determines whether CVE-2026-116588 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.
- How do I fix CVE-2026-116588?
- Upgrade
ddtraceto 3.19.9 or later - Upgrade
ddtraceto 4.15.6 or later
- Upgrade