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.
CVE-2026-59220
MEDIUMPre-NVD 6.56.5—Elevated
EchelonGraph scoreMEDIUM confidence
This medium-severity CVE scores 6.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 79% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
6.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.5Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 6.5
- EG Score
- 6.5(medium)
- EPSS
- 21.3%
- KEV
- Not listed
Published
July 9, 2026
Last Modified
July 10, 2026
Advisory Details (3)
Auto-updated Jul 9, 2026🔬 Proof of concept available. Patch available. Sources: github_release, github, github_commit.
github_release Patch Available
v0.10.0
Patch available: open-webui/open-webui v0.10.0
https://github.com/open-webui/open-webui/releases/tag/v0.10.0github_commit
commit 61a26722155e (open-webui/open-webui)
Fix landed in open-webui/open-webui commit 61a26722155e — awaiting tagged release
https://github.com/open-webui/open-webui/commit/61a26722155ec6ee1b629cf8dfcf975098c18331github Patch Available🟡 PoC Available
ReDoS in skill-mention regexes causes whole-instance DoS on default config · Advisory · open-webui/open-webui · GitHub
https://github.com/open-webui/open-webui/security/advisories/GHSA-ffpj-xv5c-p3gwWeakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Frequently asked(5)
What is CVE-2026-59220?
CVE-2026-59220 is a medium vulnerability published on July 9, 2026. Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.2 before 0.10.0, the SKILLMENTIONRE and stripre regular expressions in backend/openwebui/utils/middleware.py parsed <$skillId|label> skill mentions with overlapping quantifiers, allowing an authenticated…
When was CVE-2026-59220 disclosed?
CVE-2026-59220 was first published in the National Vulnerability Database on July 9, 2026, with the most recent update on July 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-59220 actively exploited?
CVE-2026-59220 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 21.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-59220?
CVE-2026-59220 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-59220?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59220, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-59220
Is Your Infrastructure Affected by CVE-2026-59220?
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