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CVE record · CVE-2026-55103

Discourse ActivityPub: Fix inbound actor validation and apply outbound request SSRF hardening

CVSS 8.6 HighEPSS 0.0020 · 9th percentile

Published by the CVE Program (CNA: GitHub_M) at 15 Oct 2026, 17:05 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
VendorProductVersions
discourse discourse-activity-pub
  • affected < 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5
Identifiers
CVE-2026-55103
CNA
GitHub_M
Weakness (CWE)
CWE-345 · CWE-863
Tags
Published
15 Oct 2026
Updated
28 Oct 2026

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

ScoreRatingCVSSVectorSource
8.6 High 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0020, the 9th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 15 Oct 2026. New records show when each source confirmed them.

Sources

References from the CNA

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.