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Vulnerability record · CVE-2026-84700 · published 2 September 2026

CVE-2026-84700: Missing authentication for critical function vulnerability

PikiwiDB (Pika) v3.5.7 exposes an internal protobuf replication server on a port derived from the client port plus 2000 (e.g. 11221 when the default client port 9221 is used) that does not authenticate incoming requests. Although requirepass is intended to gate replication — a slave presents it as masterauth inside its MetaSync request — only the MetaSync handler (HandleMetaSyncRequest) validates it; the frame dispatcher (DealMessage) does not require a completed or attempted MetaSync before routing other message types to their handlers. As a result, an unauthenticated remote attacker can connect directly to the replication port and issue TrySync, DBSync, BinlogSync, and RemoveSlaveNode requests, obtaining the full-sync snapshot and live write stream and removing replica nodes, even when requirepass is configured.

8.8 CVSS 4.0 High EPSS 0.58% · top 54.4% CWE-306 · Missing authentication for critical function Deferred
8.8CVSS 4.0 base score
0.58%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
4References
24 Sep 2026Last modified by NVD

Description

PikiwiDB (Pika) v3.5.7 exposes an internal protobuf replication server on a port derived from the client port plus 2000 (e.g. 11221 when the default client port 9221 is used) that does not authenticate incoming requests. Although requirepass is intended to gate replication — a slave presents it as masterauth inside its MetaSync request — only the MetaSync handler (HandleMetaSyncRequest) validates it; the frame dispatcher (DealMessage) does not require a completed or attempted MetaSync before routing other message types to their handlers. As a result, an unauthenticated remote attacker can connect directly to the replication port and issue TrySync, DBSync, BinlogSync, and RemoveSlaveNode requests, obtaining the full-sync snapshot and live write stream and removing replica nodes, even when requirepass is configured.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/OpenAtomFoundation/pikiwidb
https://github.com/OpenAtomFoundation/pikiwidb/blob/v3.5.7/src/pika_repl_server_conn.cc
https://github.com/OpenAtomFoundation/pikiwidb/issues/3270
https://www.vulncheck.com/advisories/pika-unauthenticated-replication-access-via-internal-protobuf-port

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Source: NIST National Vulnerability Database (record CVE-2026-84700), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.