CVE-2026-77399

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Source
https://cve.org/CVERecord?id=CVE-2026-77399
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-77399.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-77399
Aliases
  • GHSA-qjcq-q7h7-r74v
Downstream
Published
2026-09-22T18:58:56Z
Modified
2026-09-25T03:30:25Z
Severity
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
Summary
icalendar: Denial of service via unbounded VALARM REPEAT expansion
Details

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.

Database specific 
{
    "cna_assigner":  "GitHub_M",
    "cwe_ids":  [
        "CWE-400",
        "CWE-834"
    ],
    "osv_generated_from":  "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77399.json"
}
References

Affected packages

Git / github.com/collective/icalendar

Affected ranges

Type
GIT
Repo
https://github.com/collective/icalendar
Events
Introduced
a492d69437892bca718658487b18c632a71371c4
Fixed
157f85137c65565a308bbcf4fdcc7d8ebce01267
Fixed
cddd37226adbc52cca52a399f61d38a378221219
Fixed
ad87bcf719fde8088a77c724bc2ae8f09545e0e4
Database specific
Show details 
{
    "extracted_events":  [
        {
            "introduced":  "6.1.0"
        },
        {
            "fixed":  "7.2.2"
        }
    ],
    "source":  [
        "AFFECTED_FIELD",
        "REFERENCES"
    ]
}

Affected versions

v6.*
v6.1.0
v6.1.1
v6.1.2
v6.1.3
v6.2.0
v6.3.0
v6.3.1
v7.*
v7.0.0
v7.0.0a1
v7.0.0a2
v7.0.0a3
v7.0.1
v7.0.2
v7.0.3
v7.1.0
v7.1.1
v7.1.2
v7.1.3
v7.2.0
v7.2.1

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-77399.json"