EUVD-2026-58075
GHSA-j7xr-pwqg-qw2q
Severity by source
AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:H/A:N
PR:L reflects required Zimbra account; AC:H for JWT capture plus offline brute-force; C:L added because JWT impersonation enables reading others' documents.
Primary rating from Vendor (mitre).
CVSS VectorVendor: mitre
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:H/A:N
Lifecycle Timeline
3DescriptionCVE.org
In Zimbra Collaboration (ZCS) before 10.1.17, weak cryptographic key generation vulnerability exists in the OnlyOffice integration. The zimbraDocumentEditingJwtSecret is generated using an insecure random number generator, resulting in insufficient entropy. An attacker who obtains a JWT signed with the generated secret may be able to recover the JWT signing secret through offline brute-force, potentially enabling JWT forgery.
AnalysisAI
JWT signing secret forgery in Zimbra Collaboration before 10.1.17 stems from the zimbraDocumentEditingJwtSecret being generated with an insecure pseudo-random number generator, yielding insufficient entropy. An authenticated attacker who captures a JWT token from the OnlyOffice integration can perform offline brute-force to recover the signing secret, then mint arbitrary forged tokens - enabling impersonation or unauthorized document access within the OnlyOffice workflow. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the attacker to hold a valid Zimbra account with sufficient permissions to trigger OnlyOffice document editing (PR:L), which is necessary to obtain a legitimately-issued JWT to brute-force against. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS vector AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:H/A:N captures several important constraints: exploitation requires an authenticated Zimbra session (PR:L), high attack complexity (AC:H) due to the need to capture a JWT and then successfully brute-force the secret, and yields a scope change (S:C) reflecting that forged tokens affect the OnlyOffice subsystem. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An authenticated Zimbra user opens a document for editing, triggering issuance of a JWT signed with the low-entropy zimbraDocumentEditingJwtSecret; the attacker captures this token from network traffic or server logs, then runs an offline brute-force tool against the token to recover the signing secret. With the recovered secret, the attacker forges new JWTs impersonating arbitrary users and submits them to the OnlyOffice server to access or modify other users' documents without authorization. … |
| Remediation | Upgrade Zimbra Collaboration to version 10.1.17 or later, which resolves the insecure random number generation used to create the zimbraDocumentEditingJwtSecret. … Detailed patch versions, workarounds, and compensating controls in full report. |
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