Vulnerability-Lookup

CVE-2026-70489 (GCVE-0-2026-70489)

Vulnerability from cvelistv5 – Published: 2026-08-04 20:42 – Updated: 2026-08-04 20:42

Title

Open WebUI: Instance-wide stall via automation recurrence rules that force multi-second parsing

Summary

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.0 until 0.11.0, automation recurrence parsing in backend/open_webui/utils/automations.py anchored minutely and hourly rules at a fixed date of 2000-01-01 and then walked forward one interval at a time to find the next run. A single FREQ=MINUTELY rule enumerates roughly a quarter-century of occurrences synchronously on the event loop that also serves scheduler, HTTP, and WebSocket traffic, and the scheduler recomputes the next run for every claimed row on each poll. This causes availability impact for every other user of the instance. This issue is fixed in 0.11.0.

Severity

6.5 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CWE

CWE-400 - Uncontrolled Resource Consumption
CWE-1333 - Inefficient Regular Expression Complexity

Assigner

GitHub_M

References

3 references

URL	Tags
https://github.com/open-webui/open-webui/security…	x_refsource_CONFIRM
https://github.com/open-webui/open-webui/commit/c…	x_refsource_MISC
https://github.com/open-webui/open-webui/releases…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
open-webui	open-webui	Affected: >= 0.9.0, < 0.11.0

Show details on NVD website

JSON

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      "affected": [
        {
          "product": "open-webui",
          "vendor": "open-webui",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 0.9.0, \u003c 0.11.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.0 until 0.11.0, automation recurrence parsing in backend/open_webui/utils/automations.py anchored minutely and hourly rules at a fixed date of 2000-01-01 and then walked forward one interval at a time to find the next run. A single FREQ=MINUTELY rule enumerates roughly a quarter-century of occurrences synchronously on the event loop that also serves scheduler, HTTP, and WebSocket traffic, and the scheduler recomputes the next run for every claimed row on each poll. This causes availability impact for every other user of the instance. This issue is fixed in 0.11.0."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
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            "availabilityImpact": "HIGH",
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      "problemTypes": [
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              "cweId": "CWE-400",
              "description": "CWE-400: Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-1333",
              "description": "CWE-1333: Inefficient Regular Expression Complexity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
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        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/open-webui/open-webui/security/advisories/GHSA-73cq-mcgh-379c",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-73cq-mcgh-379c"
        },
        {
          "name": "https://github.com/open-webui/open-webui/commit/c4ae8c86786fed521960466f6d8eef8af22c2946",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/open-webui/open-webui/commit/c4ae8c86786fed521960466f6d8eef8af22c2946"
        },
        {
          "name": "https://github.com/open-webui/open-webui/releases/tag/v0.11.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/open-webui/open-webui/releases/tag/v0.11.0"
        }
      ],
      "source": {
        "advisory": "GHSA-73cq-mcgh-379c",
        "discovery": "UNKNOWN"
      },
      "title": "Open WebUI: Instance-wide stall via automation recurrence rules that force multi-second parsing"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-70489",
    "datePublished": "2026-08-04T20:42:31.752Z",
    "dateReserved": "2026-08-04T15:24:41.340Z",
    "dateUpdated": "2026-08-04T20:42:31.752Z",
    "state": "PUBLISHED"
  },
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  }
}

GHSA-73CQ-MCGH-379C

Vulnerability from github – Published: 2026-08-04 20:42 – Updated: 2026-08-04 20:42

Summary

Open WebUI: Instance-wide stall via automation recurrence rules that force multi-second parsing

Details

Summary

In every affected release, automation recurrence parsing anchors minutely and hourly rules at a fixed date of 2000-01-01 and then walks forward one interval at a time to find the next run. A single FREQ=MINUTELY rule therefore enumerates roughly a quarter-century of occurrences, synchronously, on the event loop that also serves the scheduler, HTTP and WebSocket traffic. Nothing bounds the walk, and nothing moves it off the loop.

Preconditions

Any user who can create an automation. USER_PERMISSIONS_FEATURES_AUTOMATIONS defaults to false, so on a default deployment only an admin can reach the create path; it becomes reachable by ordinary users on any deployment that has granted the automations feature, which is the normal way to make the feature usable. UVICORN_WORKERS defaults to 1, so there is no second worker to absorb the stall. The rule needs no unusual syntax: FREQ=MINUTELY with no DTSTART, or with a DTSTART set well in the past, is enough.

Impact

Availability, against every other user of the instance. One evaluation of RRULE:FREQ=MINUTELY takes 18.9 s of blocking CPU; adding a ten-value BYSECOND list multiplies the walk and takes 64.2 s. FREQ=HOURLY costs 0.34 s and is not materially exploitable on its own. The cost does not stop at creation: once the automation is stored, the scheduler recomputes the next run for every claimed row on each poll, so the same walk repeats on a default 10 s interval and the instance stays wedged rather than recovering. Instances that have not enabled the automations feature for non-admin users are exposed only to an admin doing this.

Fix

Fixed in 0.11.0. Sub-daily rules are now anchored to the current clock instead of the year-2000 date, so the walk starts at the next occurrence rather than a quarter-century behind it. A caller-supplied DTSTART is honoured only when the number of occurrences it implies stays under a fixed bound, and is otherwise replaced by the clock-aligned anchor. The same rules that cost 18.9 s and 64.2 s now cost under a millisecond. Upgrading fully resolves the issue, no configuration change is required.

Root cause

Affected component: backend/open_webui/utils/automations.py, _parse_rule, reached from the automation create, update and toggle handlers in backend/open_webui/routers/automations.py and from the scheduler's claim path in backend/open_webui/models/automations.py. Affected setup: every build from 0.9.0 onward, since that is when the automations feature shipped.

The fixed anchor existed to make sub-daily intervals snap to clock boundaries, so that "every 5 minutes" lands on :00, :05, :10 rather than drifting from whenever the automation happened to be created. Snapping only needs a reference point of the right phase, but the implementation used a literal far-past date as that reference and left the recurrence library to walk forward from it. The distance between the anchor and the present is therefore attacker-influenced work that grows with real time, and it was never treated as a cost that needed a bound or a thread.

Proof of concept

Measured cost of a single next-run computation against the shipped 0.10.2 parser:

rule	cost
`RRULE:FREQ=MINUTELY`	18,880 ms
`RRULE:FREQ=MINUTELY;BYSECOND=0,1,2,3,4,5,6,7,8,9`	64,236 ms
`DTSTART:20000101T000000` + `RRULE:FREQ=MINUTELY`	26,237 ms
`RRULE:FREQ=HOURLY`	339 ms

Measured at function level deliberately. Persisting such an automation has the scheduler repeat the walk on every poll and wedge the instance indefinitely, which is the actual impact but makes a live end-to-end run destructive to the test instance.

Credits

Reported by @Classic298.

Severity

6.5 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "open-webui"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.9.0"
            },
            {
              "fixed": "0.11.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-70489"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-1333"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-04T20:42:34Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\nIn every affected release, automation recurrence parsing anchors minutely and hourly rules at a fixed date of 2000-01-01 and then walks forward one interval at a time to find the next run. A single `FREQ=MINUTELY` rule therefore enumerates roughly a quarter-century of occurrences, synchronously, on the event loop that also serves the scheduler, HTTP and WebSocket traffic. Nothing bounds the walk, and nothing moves it off the loop.\n\n## Preconditions\nAny user who can create an automation. `USER_PERMISSIONS_FEATURES_AUTOMATIONS` defaults to `false`, so on a default deployment only an admin can reach the create path; it becomes reachable by ordinary users on any deployment that has granted the automations feature, which is the normal way to make the feature usable. `UVICORN_WORKERS` defaults to 1, so there is no second worker to absorb the stall. The rule needs no unusual syntax: `FREQ=MINUTELY` with no `DTSTART`, or with a `DTSTART` set well in the past, is enough.\n\n## Impact\nAvailability, against every other user of the instance. One evaluation of `RRULE:FREQ=MINUTELY` takes 18.9 s of blocking CPU; adding a ten-value `BYSECOND` list multiplies the walk and takes 64.2 s. `FREQ=HOURLY` costs 0.34 s and is not materially exploitable on its own. The cost does not stop at creation: once the automation is stored, the scheduler recomputes the next run for every claimed row on each poll, so the same walk repeats on a default 10 s interval and the instance stays wedged rather than recovering. Instances that have not enabled the automations feature for non-admin users are exposed only to an admin doing this.\n\n## Fix\nFixed in 0.11.0. Sub-daily rules are now anchored to the current clock instead of the year-2000 date, so the walk starts at the next occurrence rather than a quarter-century behind it. A caller-supplied `DTSTART` is honoured only when the number of occurrences it implies stays under a fixed bound, and is otherwise replaced by the clock-aligned anchor. The same rules that cost 18.9 s and 64.2 s now cost under a millisecond. Upgrading fully resolves the issue, no configuration change is required.\n\n## Root cause\nAffected component: `backend/open_webui/utils/automations.py`, `_parse_rule`, reached from the automation create, update and toggle handlers in `backend/open_webui/routers/automations.py` and from the scheduler\u0027s claim path in `backend/open_webui/models/automations.py`. Affected setup: every build from 0.9.0 onward, since that is when the automations feature shipped.\n\nThe fixed anchor existed to make sub-daily intervals snap to clock boundaries, so that \"every 5 minutes\" lands on :00, :05, :10 rather than drifting from whenever the automation happened to be created. Snapping only needs a reference point of the right phase, but the implementation used a literal far-past date as that reference and left the recurrence library to walk forward from it. The distance between the anchor and the present is therefore attacker-influenced work that grows with real time, and it was never treated as a cost that needed a bound or a thread.\n\n## Proof of concept\nMeasured cost of a single next-run computation against the shipped 0.10.2 parser:\n\n| rule | cost |\n| --- | --- |\n| `RRULE:FREQ=MINUTELY` | 18,880 ms |\n| `RRULE:FREQ=MINUTELY;BYSECOND=0,1,2,3,4,5,6,7,8,9` | 64,236 ms |\n| `DTSTART:20000101T000000` + `RRULE:FREQ=MINUTELY` | 26,237 ms |\n| `RRULE:FREQ=HOURLY` | 339 ms |\n\nMeasured at function level deliberately. Persisting such an automation has the scheduler repeat the walk on every poll and wedge the instance indefinitely, which is the actual impact but makes a live end-to-end run destructive to the test instance.\n\n## Credits\nReported by @Classic298.",
  "id": "GHSA-73cq-mcgh-379c",
  "modified": "2026-08-04T20:42:34Z",
  "published": "2026-08-04T20:42:34Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-73cq-mcgh-379c"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/commit/c4ae8c86786fed521960466f6d8eef8af22c2946"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/open-webui/open-webui"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/releases/tag/v0.11.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Open WebUI: Instance-wide stall via automation recurrence rules that force multi-second parsing"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

CVE-2026-70489 (GCVE-0-2026-70489)

GHSA-73CQ-MCGH-379C

Summary

Preconditions

Impact

Fix

Root cause

Proof of concept

Credits

Tags

Sightings

Nomenclature