CVE-2026-107276: MISP Email OTP Race Condition Allows One-Time Password to Be Consumed by Multiple Concurrent Requests

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of 29 Oct 2026. If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?

0.2%

EPSS score, percentile 11.6 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

6.3 Medium

CVSS v4.0 base score, given by the CNA

What should I do?

The fix makes OTP consumption atomic by moving the deletion of the OTP from the shared store into the validation condition itself. Full textSolution from the CVE record.

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (1)

Which versions are affected?

Affected

• before 2.5.48

Versions by product

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 29 Oct 2026. About the data.

What to do

Solution (from the CVE record)

The fix makes OTP consumption atomic by moving the deletion of the OTP from the shared store into the validation condition itself. The return value of the delete operation (1 if the key was actually removed, 0 otherwise) is now part of the success check, so only the request that successfully removes the OTP from the store is permitted to proceed with login. A session-state cleanup call was also added to remove the OTP user reference from the session.

Advisories and patches

• Security patch (Patch)

This summary is based on the CVE record as of 29 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

As listed in the CVE record.

Source: CVE List, as of 29 Oct 2026. About the data.

About this vulnerability

MISP contains a race condition in the email-based one-time password (OTP) login flow. When two HTTP requests carrying the same valid OTP are submitted concurrently, both can successfully authenticate and establish a session. The root cause is that the OTP value is read from the shared store, validated, and then deleted in separate non-atomic steps, allowing a second in-flight request to read the…

Summary: CVE record, as of 29 Oct 2026.

• CISA has not added CVE-2026-107276 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
• The CVE record was published on 7 Oct 2026.
• The CVE record carries a CVSS v4.0 base score of 6.3 (Medium), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.2% (percentile 11.6), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
• CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact partial.
• The credits in the CVE record name Anthropic (Claude) as finder.

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; CVE List, as of 29 Oct 2026; FIRST EPSS, as of 29 Oct 2026. About the data.

Description

MISP Email OTP Race Condition Allows One-Time Password to Be Consumed by Multiple Concurrent Requests

MISP contains a race condition in the email-based one-time password (OTP) login flow. When two HTTP requests carrying the same valid OTP are submitted concurrently, both can successfully authenticate and establish a session. The root cause is that the OTP value is read from the shared store, validated, and then deleted in separate non-atomic steps, allowing a second in-flight request to read the same value before the first request's deletion takes effect. Preconditions: - The target MISP instance has email OTP login enabled. - The attacker possesses a valid, unexpired OTP (e.g., via email interception or social engineering). - The attacker can issue two HTTP POST requests in close temporal proximity. Impact: - The one-time-use guarantee of the OTP is violated; a single code can yield two authenticated sessions. - This weakens the authentication control and may facilitate unauthorized access if the OTP is shared or intercepted. Affected versions: <2.5.48

Source: CVE List, as of 29 Oct 2026. About the data.

Timeline