CVE-2026-65959 — vitess

Vulnerability Details

File: go/vt/vttablet/tabletmanager/vreplication/vrlog.go

Summary

vttablet's /debug/vrlog HTTP endpoint streams live VReplication event data — including the literal SQL DML statements being replicated by MoveTables, Reshard, Materialize, and "vitess"-strategy Online DDL workflows — with no authorization check at all. Every comparable "debugging" HTTP endpoint in vttablet/vtgate (querylogz, queryz, txlogz, livequeryz, schemaz, debugenv, hotrows, tablet_plans, query_stats, query_rules) calls acl.CheckAccessHTTP(r, acl.DEBUGGING) before serving data, so that the cluster operator's configured --security-policy (e.g. deny-all, read-only, or a custom plugin) is actually honored. vrlog.go is the one exception: it has zero references to the acl package.

Root Cause

addHttpEndpoint() registers /debug/vrlog via servenv.HTTPHandleFunc, and vrlogStatsHandler() immediately starts streaming subscribed VrLogStats events to the response writer without first calling acl.CheckAccessHTTP(r, acl.DEBUGGING), unlike every sibling handler in the same family (see e.g. go/vt/vttablet/tabletserver/querylogz.go's querylogzHandler, which calls the check first).

The data streamed is sensitive: go/vt/vttablet/tabletmanager/vreplication/vplayer.go calls NewVrLogStats(...).Send(sql) / .Send(event.Statement) for every row change and statement event flowing through a VReplication stream (vplayer.go:339, 700, 771, 785) — i.e. the literal SQL (including bound data values) being copied/replicated by MoveTables, Reshard, Materialize, and Online DDL.

Attack Scenario

1. A cluster operator configures --security-policy=deny-all (or read-only, or a custom policy) specifically to lock down debugging/admin HTTP endpoints on vttablet, relying on this being uniformly enforced.
2. An attacker who can reach the vttablet debug HTTP port (common in Kubernetes/Prometheus-scraping deployments where this port is exposed beyond localhost) — but who does NOT have the DEBUGGING/admin role the policy requires — sends GET /debug/vrlog.
3. Every other debug endpoint correctly returns 403 Forbidden. /debug/vrlog returns 200 OK and streams live VReplication event data, including raw SQL DML statements containing application data values, for as long as the attacker keeps the connection open (bounded by timeout/limit query params, repeatable).

Impact

Confidentiality impact: disclosure of live replicated application data (potentially including PII or other sensitive column values) to an unauthorized actor, bypassing an access control the operator explicitly configured. No write/modify capability; this is a read-only information-disclosure / access-control-bypass issue, scoped to the vttablet debug HTTP listener.

Vulnerable Code

// go/vt/vttablet/tabletmanager/vreplication/vrlog.go
func addHttpEndpoint() {
	servenv.HTTPHandleFunc("/debug/vrlog", func(w http.ResponseWriter, r *http.Request) {
		ch := vrLogStatsLogger.Subscribe("vrlogstats")
		defer vrLogStatsLogger.Unsubscribe(ch)
		vrlogStatsHandler(ch, w, r)
	})
}

func vrlogStatsHandler(ch chan *VrLogStats, w http.ResponseWriter, r *http.Request) {
	timeout, limit := parseTimeoutLimitParams(r)
	// no acl.CheckAccessHTTP(r, acl.DEBUGGING) call anywhere in this file
	...

Recommended Fix

import "vitess.io/vitess/go/acl"

func vrlogStatsHandler(ch chan *VrLogStats, w http.ResponseWriter, r *http.Request) {
	if err := acl.CheckAccessHTTP(r, acl.DEBUGGING); err != nil {
		acl.SendError(w, err)
		return
	}
	timeout, limit := parseTimeoutLimitParams(r)
	...

This mirrors the exact pattern already used by querylogz.go, queryz.go, txlogz.go, livequeryz.go, schemaz.go, debugenv.go, and tx_serializer.go (hotrows) in the same codebase.

Verification

Built v24.0.1 from source and wrote a standalone Go test that: (1) activates the real deny-all security policy via acl.RegisterFlags, (2) registers /debug/vrlog via the real, unmodified vreplication.NewVrLogStats(...) call path (the same one vplayer.go uses for live replication traffic), (3) serves the real servenv HTTP mux on a loopback listener, and (4) issues a real GET /debug/vrlog while emitting a simulated replicated statement.

Result:

acl.CheckAccessHTTP(DEBUGGING) under deny-all => err=not allowed: deny-all security-policy enforced
GET /debug/vrlog under deny-all => status=200 body="ROWCHANGE Event\tINSERT INTO secret_table (ssn) VALUES ('leaked-via-vrlog')\t2026-06-22T11:01:55\t147101\n"

The identical ACL check that protects every sibling endpoint correctly rejected the request, while /debug/vrlog returned 200 and streamed the simulated sensitive content — confirming the bypass against real, unmodified v24.0.1 code.

Also confirmed via the GitHub Contents API that vrlog.go has zero references to the acl package on main, release-23.0, and release-22.0 as well, so all currently supported release lines appear affected.