CVE-2026-55099 evidence review
collective icalendar
icalendar is an RFC 5545 compatible parser and generator of iCalendar files for Python. From 7.1.0 until 7.1.3, the Component equality method in src/icalendar/cal/component.py compares nested subcomponents with two membership loops, and each membership test invokes the same method on child components, causing O(2^n) work relative to nesting depth. Component.from_ical accepts arbitrarily nested BEGIN:VEVENT blocks without a depth limit, so an attacker can submit a sub-kilobyte .ics file containing equal nested subtrees and trigger the cost when an application performs equality, inequality, m...
This record remains available for product and version identification, but it is not presented as a complete remediation procedure. Confirm the affected range and the supported fix in a direct vendor advisory before changing production systems.
Identify the product and installed version
Record whether collective icalendar is present, where it is installed, and which interfaces are exposed.
- Record the product name, package or appliance identifier, and installed version.
- Identify internet-facing, administrative, API, and internal access paths.
- Preserve the pre-change configuration and relevant service logs.
Compare the affected range
Use the current record as an identification aid: >= >= 7.1.0, < 7.1.3. Resolve incomplete inventory results before deciding that an asset is unaffected.
Verify the authoritative remediation source
Open the linked source material and locate a direct vendor advisory for this CVE. Confirm the supported fixed release and product-specific update path before making a production change.
Operational boundary
This page does not replace the vendor advisory, support contract, change-management process, or recovery plan. Do not infer that an asset is unaffected from an incomplete inventory query or a missing fixed-version field.