vulnerability / NVI-00015382 / Revision 1
Open WebUI: ReDoS in skill-mention regexes causes whole-instance DoS on default config
GitHub lists this reviewed advisory for open-webui. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
6.5 medium
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
open-webui
source listed>= 0.9.2, < 0.10.0
## Summary Two regexes in `backend/open_webui/utils/middleware.py` that parse `` skill-mention tags backtrack in O(n²) on input that contains ``. Both run synchronously, on the asyncio event loop, on **every** chat completion with no feature gate. Because the default deployment is a single uvicorn worker, one such input pins a CPU core inside `re` and freezes the entire instance for all users until the worker is killed. Any authenticated user can trigger it with one chat message; it also fires accidentally on benign retrieved content (a RAG chunk or tool output) containing the pattern. ## Affected versions `>= 0.9.2, < 0.10.0`. Fixed in **v0.10.0** (there is no 0.9.7 release). - `SKILL_MENTION_RE` (the extract pattern) has been O(n²) since **v0.9.2**; exploitable on 0.9.2–0.9.5 with a large input (hundreds of KB). - **v0.9.6** added a second, far more aggressive O(n²) in the strip pattern (introduced by the "keep label as readable text" change), so on 0.9.6 a small input is enough to hang the instance. Both are fixed by the same patch. ## Affected component `backend/open_webui/utils/middleware.py` (line numbers as of v
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-ffpj-xv5c-p3gw ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.