CVE-2026-55099 - icalendar: Algorithmic Complexity in Equality
Brief
CVE ID : CVE-2026-55099
Published : Aug. 25, 2026, 8:16 p. m.
- 55 minutes ago
Description : icalendar is an RFC 5545 compatible parser and generator of iCalendar files for Python. From 7.
- 0 until 7.
- 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, membership, deduplication, test-assertion, round-trip, or normalization comparisons.