CVE-2026-27801

Vaultwarden has 2FA Bypass on Protected Actions due to Faulty Rate Limit Enforcement

An attacker who gains access to a user’s account can exploit this bypass to perform protected actions such as accessing the user’s API key or deleting the user’s accounts and organisations.

Kodem intelligence

The simplest fix is to ensure the updated number of attempts is persisted by calling pa.data = pa_data.to_json() before calling pa.save(conn). However this still leaves open the possibility of an attacker requesting an OTP code, exhausting their six attempts and then requesting a new code to try. This attack succeeds with probability

1 - \left(1 - \frac{6}{10^L}\right)^n,

which becomes non-neglible as $n$ increases.

Therefore the best approach might be to enforce a delay like this, to ensure that all rate limits are ultimately tied back to time:

diff --git a/src/api/core/two_factor/protected_actions.rs b/src/api/core/two_factor/protected_actions.rs
index 5e4a65be..aa9cb8f6 100644
--- a/src/api/core/two_factor/protected_actions.rs
+++ b/src/api/core/two_factor/protected_actions.rs
@@ -66,7 +66,18 @@ async fn request_otp(headers: Headers, mut conn: DbConn) -> EmptyResult {
     if let Some(pa) =
         TwoFactor::find_by_user_and_type(&user.uuid, TwoFactorType::ProtectedActions as i32, &mut conn).await
     {
-        pa.delete(&mut conn).await?;
+        let pa_data = ProtectedActionData::from_json(&pa.data)?;
+        let token_sent = DateTime::from_timestamp(pa_data.token_sent, 0)
+            .expect("Protected Action token timestamp invalid")
+            .naive_utc();
+        let elapsed = Utc::now().naive_utc() - token_sent;
+        let delay = TimeDelta::seconds(20);
+
+        if elapsed < delay {
+            err!(format!("Please wait {} seconds before requesting another code.", (delay - elapsed).num_seconds()));
+        } else {
+            pa.delete(&mut conn).await?;
+        }
     }

     let generated_token = crypto::generate_email_token(CONFIG.email_token_size());
@@ -131,6 +142,7 @@ pub async fn validate_protected_action_otp(
     }

     if !crypto::ct_eq(&pa_data.token, otp) {
+        pa.data = pa_data.to_json();
         pa.save(conn).await?;
         err!("Token is invalid")
     }

1. What is CVE-2026-27801? CVE-2026-27801 is a medium-severity security vulnerability in vaultwarden (rust), affecting versions <= 1.34.3. It is fixed in 1.35.0.
2. Which versions of vaultwarden are affected by CVE-2026-27801? vaultwarden (rust) versions <= 1.34.3 is affected.
3. Is there a fix for CVE-2026-27801? Yes. CVE-2026-27801 is fixed in 1.35.0. Upgrade to this version or later.
4. Is CVE-2026-27801 exploitable, and should I be worried? Whether CVE-2026-27801 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
5. What actually determines whether CVE-2026-27801 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.
6. How do I fix CVE-2026-27801? Upgrade vaultwarden to 1.35.0 or later.