CVE-2026-59220 json
Open WebUI: ReDoS in skill-mention regexes causes whole-instance DoS on default config
published 2026-07-09 4 mo ago modified 2026-08-04 3 mo ago also GHSA-ffpj-xv5c-p3gw , PYSEC-2026-3596 , EUVD-2026-42621
- cvss
- 6.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.6%
- EPSS 0.6% chance of exploitation in 30 days, percentile 47%
- public exploits
- 0
- none known
Summary
Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.2 before 0.10.0, the SKILL_MENTION_RE and strip_re regular expressions in backend/open_webui/utils/middleware.py parsed <$skillId|label> skill mentions with overlapping quantifiers, allowing an authenticated chat message containing <$ without a closing > to trigger quadratic backtracking and block the asyncio event loop. This issue is fixed in version 0.10.0.
Patch / fix
- pypi open-webui 0.10.0
- openwebui open_webui 0.10.0
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 4 mo ago
Exploit prediction
0.57% chance of exploitation in the next 30 days, higher than 47% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gw referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| OSV | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| GitHub | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | open-webui | >=0.9.2, <0.10.0 |
0.10.0 |
Affected products
- open-webui open-webui
Classification
- Weakness
-
- CWE-1333 Inefficient Regular Expression Complexity
References
-
github.com
/open-webui/open-webui/commit/61a26722155ec6ee1b629cf8dfcf975098c18331
web, patch
-
github.com
/open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gw
exploit, web, mitigation, vendor-advisory
-
github.com
/open-webui/open-webui/releases/tag/v0.10.0
web, product, release-notes
-
nvd.nist.gov
/vuln/detail/CVE-2026-59220
advisory
-
github.com
/open-webui/open-webui
package
-
pypi.org
/project/open-webui
package
-
github.com
/advisories/GHSA-ffpj-xv5c-p3gw
advisory
Sources
- CVE List CVE-2026-59220
- GitHub Advisory GHSA-ffpj-xv5c-p3gw
- NVD CVE-2026-59220
- OSV PYSEC-2026-3596
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.