GHSA-45hj-9x76-wp9g

Summary

This vulnerability allows a user i.e a free plan user to get more than the desired subdomains due to lack of db transaction lock mechanisms in https://github.com/akinloluwami/outray/blob/main/apps/web/src/routes/api/%24orgSlug/subdomains/index.ts

Details

• The affected code-:

  //Race condition
          const [subscription] = await db
            .select()
            .from(subscriptions)
            .where(eq(subscriptions.organizationId, organization.id));
  
          const currentPlan = subscription?.plan || "free";
          const planLimits = getPlanLimits(currentPlan as any);
          const subdomainLimit = planLimits.maxSubdomains;
  
          const existingSubdomains = await db
            .select()
            .from(subdomains)
            .where(eq(subdomains.organizationId, organization.id));
  
          if (existingSubdomains.length >= subdomainLimit) {
            return json(
              {
                error: `Subdomain limit reached. The ${currentPlan} plan allows ${subdomainLimit} subdomain${subdomainLimit > 1 ? "s" : ""}.`,
              },
              { status: 403 },
            );
          }
  
          const existing = await db
            .select()
            .from(subdomains)
            .where(eq(subdomains.subdomain, subdomain))
            .limit(1);
  
          if (existing.length > 0) {
            return json({ error: "Subdomain already taken" }, { status: 409 });
          }
  
          const [newSubdomain] = await db
            .insert(subdomains)
            .values({
              id: crypto.randomUUID(),
              subdomain,
              organizationId: organization.id,
              userId: session.user.id,
            })
            .returning();
  

• The first part of the code checks the user plan and determine his/her existing_domains without locking the transaction and allowing it to run.

  const existingSubdomains = await db
            .select()
            .from(subdomains)
            .where(eq(subdomains.organizationId, organization.id));
  

• The other part of the code checks if the desired domain is more than the limit.

  if (existingSubdomains.length >= subdomainLimit) {
            return json(
              {
                error: `Subdomain limit reached. The ${currentPlan} plan allows ${subdomainLimit} subdomain${subdomainLimit > 1 ? "s" : ""}.`,
              },
              { status: 403 },
            );
          }
  

• Finally, it inserts the subdomain also after the whole check without locking transactions.

  const [newSubdomain] = await db
            .insert(subdomains)
            .values({
              id: crypto.randomUUID(),
              subdomain,
              organizationId: organization.id,
              userId: session.user.id,
            })
            .returning();
  

• An attacker can exploit this by making parallel requests to the same endpoint and if the second request reads row subdomains before the INSERT statement of request one is made.It allows the attacker to act on a not yet updated row which bypasses the checks and allow the attacker to get more subdomains.For example-:

    Parallel request 1                               Parallel  Request  2    
       |                                                                     |
  checks for                                                     Checks the not yet updated
  available subdomain                                     row and bypasses the logic checks
  and determines if it is more than limit
      |                                                                        |
  Inserts subdomain and calls it a day           Also inserts the  subdomain
  

• The attack focuses on exploiting the race window between reading and writing the db rows.

PoC

• Intercept with Burp proxy,pass to Repeater and create multiple requests in a single batch with different subdomain names as seen below. Lastly, send the requests in parallel.

<img width="1844" height="855" alt="image" src="https://github.com/user-attachments/assets/f46d5993-31bd-4b96-902a-b2de5b0518bd" />

• Result-:

<img width="1905" height="977" alt="image" src="https://github.com/user-attachments/assets/4c877de2-4b55-46f4-9f1c-78590dfebefc" />

Impact

The vulnerability provides an infiinite supply of domains to users bypassing the need for subscription