CVE-2026-55759 RocketChat CVE debrief

Who should care

Defenders responsible for Rocket.Chat instances, particularly those using Apple Sign-In, should assess exposure and apply patches to prevent authentication bypass. This includes verifying exposure, applying patches, and monitoring for potential replay attacks using Apple identity tokens. The vulnerability has a CVSS score of 7.4 and is considered high-severity. Rocket.Chat instances using Apple Sign-In are potentially affected.

Why it matters

CVE-2026-55759 is a high-severity vulnerability in Rocket.Chat's Apple Sign-In handler that allows an attacker to replay a target user's Apple identity token to authenticate as that user. Defenders responsible for Rocket.Chat instances, particularly those using Apple Sign-In, should assess exposure and apply patches to prevent authentication bypass. The vulnerability has a CVSS score of 7.4 and is fixed in Rocket.Chat versions 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13.

• Potential authentication bypass using replayed Apple identity tokens.
• Increased risk of unauthorized access to Rocket.Chat instances.
• Need for verification of exposure and application of patches.
• Potential for monitoring and incident response plan updates.

Technical summary

The Rocket.Chat Apple Sign-In handler verifies JWT signatures but skips claims validation, allowing an attacker to replay a target user's Apple identity token to authenticate as that user. This vulnerability has a CVSS score of 7.4 and is considered high-severity. The vulnerability is fixed in Rocket.Chat versions 8.5.1, 8.4.4, 8.3.6, 8.2.6, 8.1.6, 8.0.7, and 7.10.13. Defenders should prioritize verifying exposure and applying patches due to the high severity and potential for authentication bypass. Rocket.Chat instances using Apple Sign-In are potentially affected.

Defensive priority

Defenders should prioritize verifying exposure and applying patches due to the high severity and potential for authentication bypass.

Recommended defensive actions

• Verify if Rocket.Chat instances are using Apple Sign-In and assess exposure.
• Apply patches to Rocket.Chat instances to prevent authentication bypass.
• Monitor for potential replay attacks using Apple identity tokens.
• Review and update incident response plans to address potential authentication bypass.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. A GitHub security advisory also provides additional context. The vulnerability allows an attacker to replay a target user's Apple identity token to authenticate as that user. Defenders should verify exposure and apply patches to prevent authentication bypass. The CVE record was published on 2026-06-24T22:16:49.527Z and has not been modified since then. The vulnerability has a CVSS score of 7.4 and is fixed.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.