Vulnerability record

CVE-2025-30355

A permanent, source-backed tracker page. Values are shown only when returned; explicit gaps and read failures remain different states.

Full record read. Reported values and explicit gaps below come from the tracked record. Tracker snapshot: Aug 9, 2026.

What it is

Reported

Synapse is an open source Matrix homeserver implementation. A malicious server can craft events which, when received, prevent Synapse version up to 1.127.0 from federating with other servers. The vulnerability has been exploited in the wild and has been fixed in Synapse v1.127.1. No known workarounds are available. Source description excerpt; complete tracked detail loads below.

NVD published: Mar 27, 2025 · Source record updated: Aug 9, 2026 · Tracker snapshot: Aug 9, 2026

What is affected

Reported

Element — Synapse. Product-level identification only; no affected-version conclusion is available from this field.

NVD published: Mar 27, 2025 · Source record updated: Aug 9, 2026 · Tracker snapshot: Aug 9, 2026

Urgency and basis

Reported

Act · 441.8

Tracker decision tier from the evidence detailed below · Source record updated: Aug 9, 2026 · Tracker snapshot: Aug 9, 2026

Exploitation evidence

Reported

kev-listed · VulnCheck KEV

VulnCheck KEV added: Mar 26, 2025 · Source record updated: Aug 9, 2026 · Tracker snapshot: Aug 9, 2026

What to do

Reported

Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.

Source remediation ↗

Tracked source remediation field · Source record updated: Aug 9, 2026 · Tracker snapshot: Aug 9, 2026

Evidence detail

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