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CVE-2026-63462: Unleash: Unauthenticated single-request DoS via OpenAPI validation error formatter

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-21 · updated 2026-10-14
• Weakness: CWE-674

Description

Unleash is an open-source feature management platform. Prior to 7.5.2, 7.6.5, and 8.0.2, the shared OpenAPI validation error path in src/lib/error/bad-data-error.ts passes a raw request value from lodash.get to JSON.stringify in genericErrorMessage and fromOpenApiValidationErrors without guarding stack exhaustion. An unauthenticated attacker can send a roughly 10 KB JSON value nested thousands of levels deep to POST /edge/validate, POST /edge/issue-token, or another OpenAPI-validated endpoint, causing RangeError: Maximum call stack size exceeded in openAPIValidationMiddleware and terminating the Node process because no uncaughtException handler recovers it. Replaying the request can sustain a complete service outage. This issue is fixed in versions 7.5.2, 7.6.5, and 8.0.2.

Affected products

• unleash: before 7.5.2; from 7.6.0, < 7.6.5; from 8.0.0, < 8.0.2

References

• https://github.com/Unleash/unleash/commit/b0e4da63249a9403bc209e0581db223326cb8dcf
• https://github.com/Unleash/unleash/commit/d45f99df924c0d24747b3e45e46fcda7dcd3c1c1
• https://github.com/Unleash/unleash/commit/d862562a5ab8f2d1e40f6519c64cf0b4fdaf806d
• https://github.com/Unleash/unleash/releases/tag/v7.5.2
• https://github.com/Unleash/unleash/releases/tag/v7.6.5
• https://github.com/Unleash/unleash/releases/tag/v8.0.2
• https://github.com/Unleash/unleash/security/advisories/GHSA-r5pq-6chh-j3xp
• https://github.com/Unleash/unleash/security/advisories/GHSA-r5pq-6chh-j3xp

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