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.
CVE-2026-55759
HIGHPre-NVD 7.47.4—
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 85% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
7.4
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.4Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.4
- EG Score
- 7.4(medium)
- EPSS
- 15.4%
- KEV
- Not listed
Published
June 24, 2026
Last Modified
June 26, 2026
Advisory Details (1)
Auto-updated Jun 25, 2026Patch available. Sources: github.
github Patch Available
Apple Sign-In skips JWT claims validation, allowing expired and cross-audience token replay · Advisory · RocketChat/Rocket.Chat · GitHub
https://github.com/RocketChat/Rocket.Chat/security/advisories/GHSA-c75c-5hc7-j4vpFrequently asked(5)
What is CVE-2026-55759?
CVE-2026-55759 is a high vulnerability published on June 24, 2026. 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…
When was CVE-2026-55759 disclosed?
CVE-2026-55759 was first published in the National Vulnerability Database on June 24, 2026, with the most recent update on June 26, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55759 actively exploited?
CVE-2026-55759 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 15.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-55759?
CVE-2026-55759 has a CVSS v3 base score of 7.4 (NVD).
How do I remediate CVE-2026-55759?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55759, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-55759
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