python-icalendar — security advisory

{
  "id": "f78562130aa989957cb01de3923a68b29f1c56880be3bf934ff9842cf2f7bd21",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-77399",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2026-77399",
    "summary": "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.",
    "evidence": "osv:DEBIAN-CVE-2026-77399",
    "products": [
      {
        "name": {
          "value": "python-icalendar",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.3.0-1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "6.0.1-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.0.1-3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.3.1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.3.1-2",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "DEBIAN-CVE-2026-77399",
      "aliases": [
        "DEBIAN-CVE-2026-77399"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "7.3.0-1"
                }
              ]
            }
          ],
          "package": {
            "name": "python-icalendar",
            "purl": "pkg:deb/debian/python-icalendar?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "versions": [
            "6.0.1-2",
            "6.0.1-3",
            "6.3.1-1",
            "6.3.1-2"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-77399.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-09T17:00:11.482092814Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-77399"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2026-77399"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-77399",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 122319,
  "published_at": "2026-09-22T19:16:51.443+00:00"
}