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Omnivore EUVDEUVD-2026-68109

| CVE-2026-82454 CRITICAL
Improper Verification of Cryptographic Signature (CWE-347)
2026-08-29 VulnCheck GHSA-8fpq-5wcx-76h3
9.3
CVSS 4.0 · Vendor: VulnCheck
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Vendor (VulnCheck) PRIMARY
9.3 CRITICAL
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
9.1 CRITICAL

Remote, unauthenticated, low-complexity token forgery gives full account impersonation (C:H/I:H); no availability impact and no scope change beyond the authenticating service.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

3
Source Code Evidence Fetched
Aug 29, 2026 - 14:37 vuln.today
Analysis Generated
Aug 29, 2026 - 14:37 vuln.today
CVE Published
Aug 29, 2026 - 13:47 cve.org
CRITICAL 9.3

DescriptionCVE.org

The Omnivore API (packages/api) before the fix in commit abf53d6 contains an authentication bypass in Apple sign-in token verification. The decodeAppleToken function extracted the 'alg' field from the attacker-supplied JWT header and passed it as the sole allowed algorithm to jwt.verify(). Using jsonwebtoken v8 (which does not validate key/algorithm compatibility), an attacker can set alg=HS256 and sign a forged token using Apple's publicly available RSA public key as the HMAC secret, bypassing signature verification and impersonating any Apple-linked account.

AnalysisAI

Authentication bypass in the Omnivore API (packages/api) before commit abf53d6 lets a remote unauthenticated attacker impersonate any Apple-linked account through a JWT algorithm-confusion flaw in Apple sign-in. Because decodeAppleToken trusted the attacker-controlled 'alg' header and jsonwebtoken v8 does not enforce key/algorithm compatibility, an attacker can switch the token to HS256 and sign it with Apple's public RSA key used as the HMAC secret. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
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Vulnerability AssessmentAI

Exploitation Exploitation requires that the Omnivore deployment has Apple sign-in enabled and is running the vulnerable API (packages/api before commit abf53d6) built against jsonwebtoken v8, whose failure to validate key/algorithm compatibility is essential to the attack. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a genuine high-priority issue rather than an inflated CVSS number: the CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H) describes remote, unauthenticated, low-complexity exploitation yielding full account takeover, and the underlying algorithm-confusion technique is public and trivially scriptable, so any operator running an unpatched instance should treat it as urgent. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Upstream fix available (PR/commit); a released, tagged patched version is not independently confirmed - apply the change in commit abf53d6508755d3d22a994e28e370a9193ea977a (PR https://github.com/omnivore-app/omnivore/pull/4652), which hardcodes algorithms to ['RS256'] in jwt.verify() and stops reading 'alg' from the token header. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, audit access logs for anomalous authentication activity on Apple-linked accounts and initiate patch deployment planning. …

Sign in for detailed remediation steps and compensating controls.

Threat intelligence, references, and detailed analysis are available after sign-in.

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EUVD-2026-68109 vulnerability details – vuln.today

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