CVE-2026-55759
CVE-2026-55759 is a high-severity vulnerability with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.
Key facts
- Severity: High (CVSS 3.x base score 7.4)
- EPSS exploit prediction: 0% (15th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-39120
- Weakness: CWE-287
- Published:
- Last modified:
Description
Rocket.Chat is an open-source, secure, fully customizable communications platform. Prior to 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13, Rocket.Chat's Apple Sign-In handler verifies JWT signatures but skips claims validation. Any Apple-signed JWT with a non-empty iss is accepted regardless of aud, exp, nbf, or nonce. An attacker who obtains a target user's Apple identity token (from server logs, an intercepted sign-in flow, or another application sharing the same Apple developer team) can replay it to authenticate as that user, with no expiration on the replay window. This vulnerability is fixed in 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13.
Frequently asked questions
- What is CVE-2026-55759?
- Rocket.Chat is an open-source, secure, fully customizable communications platform. Prior to 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13, Rocket.Chat's Apple Sign-In handler verifies JWT signatures but skips claims validation. Any Apple-signed JWT with a non-empty iss is accepted regardless of aud, exp, nbf, or nonce. An attacker who obtains a target user's Apple identity token (from server logs, an intercepted sign-in flow, or another application sharing the same Apple developer team) can replay it to authenticate as that user, with no expiration on the replay window. This vulnerability is fixed in 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13.
- How severe is CVE-2026-55759?
- CVE-2026-55759 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
- Is CVE-2026-55759 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-55759?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-55759 have an EU (EUVD) identifier?
- Yes. CVE-2026-55759 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39120.
- When was CVE-2026-55759 published?
- CVE-2026-55759 was published on 2026-06-24 and last updated on 2026-06-26.
References
Other CWE-287 (Improper Authentication) vulnerabilities
- CVE-2026-45480 — Critical (CVSS 10.0): Improper authentication in Azure Active Directory allows an unauthorized attacker to elevate privileges over a network.
- CVE-2026-46389 — Critical (CVSS 10.0): UDS Identity Config builds the Keycloak configuration image (realm, plugins, theme, truststore, JARs) consumed by UDS…
- CVE-2026-10611 — Critical (CVSS 10.0): An authentication bypass vulnerability exists in MISP when LDAP mixed authentication is enabled with OTP enforcement.…
- CVE-2026-47280 — Critical (CVSS 10.0): Improper authentication in Azure Resource Manager (ARM) allows an unauthorized attacker to elevate privileges over a…
- CVE-2026-42822 — Critical (CVSS 10.0): Improper authentication in Azure Local Disconnected Operations allows an unauthorized attacker to elevate privileges…
- CVE-2026-20182 — Critical (CVSS 10.0): May 2026: This security advisory provides the details and fix information for a vulnerability that was discovered and…
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