Summary
Vitess: Missing authorization on vttablet /debug/vrlog exposes live VReplication SQL data
Vulnerability Details
File: go/vt/vttablet/tabletmanager/vreplication/vrlog.go
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
- A cluster operator configures
--security-policy=deny-all(orread-only, or a custom policy) specifically to lock down debugging/admin HTTP endpoints on vttablet, relying on this being uniformly enforced. - 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, sendsGET /debug/vrlog. - Every other debug endpoint correctly returns
403 Forbidden./debug/vrlogreturns200 OKand 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 bytimeout/limitquery params, repeatable).
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
...
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.
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.
The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.
CVE-2026-65959 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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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.
Frequently Asked Questions
- What is CVE-2026-65959? CVE-2026-65959 is a medium-severity missing authorization vulnerability in vitess.io/vitess (go), affecting versions >= 0.24.0-rc1, <= 0.24.2. No fixed version is listed yet. The application does not perform an authorization check before performing a sensitive operation.
- How severe is CVE-2026-65959? CVE-2026-65959 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of vitess.io/vitess are affected by CVE-2026-65959? vitess.io/vitess (go) versions >= 0.24.0-rc1, <= 0.24.2 is affected.
- Is there a fix for CVE-2026-65959? No fixed version is listed for CVE-2026-65959 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2026-65959 exploitable, and should I be worried? Whether CVE-2026-65959 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-65959 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-65959? No fixed version is listed yet. In the interim: Keep the dependency up to date. Ensure authorization checks are enforced consistently on all sensitive operations.