CVE-2026-77399: CWE-400: Uncontrolled Resource Consumption in collective icalendar
icalendar is an RFC 5545 compatible parser and generator of iCalendar files for Python. From 6.1.0 until 7.2.2, vInt.from_ical accepts an attacker-controlled VALARM REPEAT value and applications that request alarm times can eagerly expand it without an application-level limit. Alarms.times and Alarms.active reach the unbounded expansion in versions starting with 6.1.0, while Alarm.triggers adds a second affected path starting with 7.0.0. Parsing alone does not trigger the issue, but accessing these properties can consume excessive CPU time and heap memory and terminate or stall a service. This issue is fixed in version 7.2.2.
AI Analysis
Technical Summary
The collective icalendar Python package, which parses and generates iCalendar files, contains a resource consumption vulnerability (CWE-400) in versions 6.1.0 through 7.2.1. The function vInt.from_ical accepts an attacker-controlled VALARM REPEAT value without application-level limits. Accessing properties such as Alarms.times, Alarms.active (from 6.1.0), and Alarm.triggers (from 7.0.0) can trigger unbounded expansion of alarm times, leading to excessive CPU and heap memory consumption. This can cause service termination or stalling. The vulnerability does not trigger on parsing alone but requires property access. The issue is resolved in version 7.2.2.
Potential Impact
Exploiting this vulnerability can cause denial of service by exhausting CPU and memory resources when alarm-related properties are accessed. There is no impact on confidentiality or integrity. The service using the vulnerable icalendar versions may stall or terminate unexpectedly due to resource exhaustion.
Mitigation Recommendations
Upgrade to collective icalendar version 7.2.2 or later, where this vulnerability is fixed. No other mitigation is indicated or required.
CVE-2026-77399: CWE-400: Uncontrolled Resource Consumption in collective icalendar
Description
icalendar is an RFC 5545 compatible parser and generator of iCalendar files for Python. From 6.1.0 until 7.2.2, vInt.from_ical accepts an attacker-controlled VALARM REPEAT value and applications that request alarm times can eagerly expand it without an application-level limit. Alarms.times and Alarms.active reach the unbounded expansion in versions starting with 6.1.0, while Alarm.triggers adds a second affected path starting with 7.0.0. Parsing alone does not trigger the issue, but accessing these properties can consume excessive CPU time and heap memory and terminate or stall a service. This issue is fixed in version 7.2.2.
CVSS v3.1
Score 6.5medium
Affected software
collective
icalendar
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The collective icalendar Python package, which parses and generates iCalendar files, contains a resource consumption vulnerability (CWE-400) in versions 6.1.0 through 7.2.1. The function vInt.from_ical accepts an attacker-controlled VALARM REPEAT value without application-level limits. Accessing properties such as Alarms.times, Alarms.active (from 6.1.0), and Alarm.triggers (from 7.0.0) can trigger unbounded expansion of alarm times, leading to excessive CPU and heap memory consumption. This can cause service termination or stalling. The vulnerability does not trigger on parsing alone but requires property access. The issue is resolved in version 7.2.2.
Potential Impact
Exploiting this vulnerability can cause denial of service by exhausting CPU and memory resources when alarm-related properties are accessed. There is no impact on confidentiality or integrity. The service using the vulnerable icalendar versions may stall or terminate unexpectedly due to resource exhaustion.
Mitigation Recommendations
Upgrade to collective icalendar version 7.2.2 or later, where this vulnerability is fixed. No other mitigation is indicated or required.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-20T19:55:27.023Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ab2d481f7a7c54106a364cd
Added to database: 09/22/2026, 19:18:25 UTC
Last enriched: 09/22/2026, 19:33:45 UTC
Last updated: 09/23/2026, 01:58:06 UTC
Views: 9
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