CVE WatchNov 13, 2026

CVE-2026-126360

OpenTelemetry Python provides the Python API and SDK for OpenTelemetry. Prior to 1.45.2, TraceContextTextMapPropagator.extract() in opentele

CVSS

5.3

Medium

EPSS

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KEV

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Exploit Today

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0-100

Published: Nov 13, 2026 · Last modified: Nov 13, 2026 · CWE-1333

EPSS · 30d

Not enough EPSS history yet.

Technical description

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.

Official references

Related CVEs

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CVE-2026-1263535.9 MED

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———Addressable is an alternative implementation to the URI implementation that is part of Ruby's standard library. From 2.3.0 until 2.9.1, URI template expressions containing several exploded variables generate ambiguous regular expressions that can divide a run of members among the variables in polynomially many ways. Template#match or Template#extract processing of an attacker-controlled URI can therefore consume a thread and cause denial of service. The flaw affects MRI Ruby before 3.2 and JRuby, TruffleRuby 40.0, and plus or number-sign expressions on MRI Ruby 3.2. MRI Ruby 3.3 and later, URI parsing, and Template#expand are unaffected. This issue is fixed in version 2.9.1.4h CVE-2026-1263525.9 MED

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———Addressable is an alternative implementation to the URI implementation that is part of Ruby's standard library. From 2.3.0 until 2.9.1, URI templates with several variables in one expression or several adjacent expressions generate ambiguous regular expressions. Affected forms include multi-variable expressions using operators other than plus and number sign, large plus or number-sign expressions, and adjacent single-variable expressions. Template#match or Template#extract can backtrack polynomially or exponentially on attacker-controlled URIs, causing denial of service on MRI Ruby before 3.2 and JRuby, with the large plus and number-sign form also affecting MRI Ruby 3.2 and TruffleRuby 40.0. URI parsing and Template#expand are unaffected. This issue is fixed in version 2.9.1.4h CVE-2026-1263505.9 MED

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———Addressable is an alternative implementation to the URI implementation that is part of Ruby's standard library. From 2.3.0 until 2.9.1, URI template expressions using the explode modifier with the slash, dot, semicolon, question-mark, or ampersand operators generate ambiguous regular expressions. When Template#match or Template#extract processes an attacker-controlled URI beginning with the operator's leading character, optional member separators allow catastrophic backtracking and denial of service on MRI Ruby before 3.2 and JRuby. Addressable 2.9.0 incompletely remediated the earlier template issue because its tests did not reach these operator-prefixed paths. URI parsing and Template#expand are unaffected. This issue is fixed in version 2.9.1.4h CVE-2026-1262055.3 MED

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———Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. Prior to 2.25.3, the Loofah HTML5 sanitizer checks href and xlink:href on elements in SVG_ALLOW_LOCAL_HREF with a regular expression whose line anchor and newline-matching whitespace cause an all-whitespace value to be rescanned from every line start. An attacker can submit an SVG reference element with a long multiline-whitespace attribute and consume CPU quadratically during sanitization. CRuby 3.1 and earlier and JRuby are affected, while CRuby 3.2 and later uses linear-time regular-expression matching. The default safelist reaches the vulnerable check without a configuration change. This issue is fixed in version 2.25.3.5h CVE-2026-1261917.5 HIG

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———Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 3.0, the CSS_ESCAPES and IDENTIFIER regular-expression subpatterns can backtrack exponentially on runs of ambiguous digit escapes in an attribute-name or tag position of an otherwise valid selector. The failure occurs during selector compilation through soupsieve.compile() or Beautiful Soup select() before SELECTOR_LIMIT is applied, so an application that accepts untrusted selector strings can have a worker stalled by a short input. This issue is fixed in version 3.0.8h CVE-2026-61619—

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——0The OWASP core rule set (CRS) is a set of generic attack detection rules for use with compatible web application firewalls. Prior to versions 3.3.10, 4.25.1, and 4.28.0, regular-expression denial of service (ReDoS) affects a shared regex-assembly include used to build 12 Unix RCE detection rules in CRS v4, and the same ambiguous pattern was present in the manually-assembled regexes in 4 rules in CRS v3.3. With a single, unauthenticated, crafted request, the generated pattern drives PCRE2 past its backtracking limit. When PCRE2 exceeds that limit, the @rx operator returns an error rather than a match result, which results in detection bypass and CPU denial of service. This issue has been patched in versions 3.3.10, 4.25.1, and 4.28.0.5h