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CVE-2026-55759

HIGHCVSS 7.4/10EPSS 0.24%

Last modified

CVE-2026-55759 is a high-severity vulnerability rated 7.4/10 on the CVSS scale. 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. EPSS estimates a 0.24% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.4/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS Probability
0.24%

15.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

References

Timeline

Published
Last Modified
Status
Deferred

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 score of 7.4/10 (HIGH severity). The EPSS model estimates a 0.24% probability of exploitation in the next 30 days.
How do I fix CVE-2026-55759?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-55759?

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Source: NVD / NIST