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Advisory record · GHSA-rxpg-wjf8-qv9c

Yamcs has Reflected XSS in the URL of the Authorize Endpoint

CVSS 6.5 MediumEPSS 0.013 · 70th percentile

Published by the GitHub Advisory Database at 28 Aug 2026, 17:17 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
org.yamcs:yamcs-coreMaven<5.9.45.9.4
Identifiers
GHSA-rxpg-wjf8-qv9c · CVE-2026-55549
Weakness (CWE)
CWE-79
Tags
Published
28 Aug 2026
Updated
28 Aug 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Yamcs (org.yamcs:yamcs-core) versions before 5.9.4 are vulnerable to reflected cross-site scripting in the URL of the authorize endpoint. An attacker can get a user to open a crafted link, which runs arbitrary JavaScript in the user's browser and can expose the user's access and refresh tokens, allowing account takeover. Upgrade to yamcs-core 5.9.4 or later.

Written 2 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
6.5 Medium 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.013, the 70th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:19 UTC First seen by agentprime
  2. 31 Oct 2026, 14:19 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.