A time-of-check/time-of-use (TOCTOU) race condition in fastschema through v0.15.1 allows an unauthenticated remote attacker to bypass the OTP attempt limit on the account recovery flow, enabling brute-force attacks on 6-digit OTP codes.

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00246.

Exploitation none

Automatable no

Technical Impact total

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
fastschema fastschema unknown
Version Status Constraints
0 affected ≤ 0.15.1

No data.

No data.

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Advisories

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Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/fastschema/fastschema cve-icon cve-icon
https://github.com/fastschema/fastschema/blob/main/pkg/auth/local.go cve-icon cve-icon
History

Tue, 11 Aug 2026 15:45:00 +0000

Type Values Removed Values Added
First Time appeared Fastschema
Fastschema fastschema
Vendors & Products Fastschema
Fastschema fastschema

Mon, 10 Aug 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Mon, 10 Aug 2026 12:00:00 +0000

Type Values Removed Values Added
Description A time-of-check/time-of-use (TOCTOU) race condition in fastschema through v0.15.1 allows an unauthenticated remote attacker to bypass the OTP attempt limit on the account recovery flow, enabling brute-force attacks on 6-digit OTP codes. The verifyOTPSession function in pkg/auth/local.go reads and increments the attempt counter in separate non-atomic operations, allowing concurrent requests to observe the same attempt count below the threshold and proceed past the limit check before any update is committed. A time-of-check/time-of-use (TOCTOU) race condition in fastschema through v0.15.1 allows an unauthenticated remote attacker to bypass the OTP attempt limit on the account recovery flow, enabling brute-force attacks on 6-digit OTP codes.

Mon, 10 Aug 2026 11:00:00 +0000

Type Values Removed Values Added
Description A time-of-check/time-of-use (TOCTOU) race condition in fastschema through v0.15.1 allows an unauthenticated remote attacker to bypass the OTP attempt limit on the account recovery flow, enabling brute-force attacks on 6-digit OTP codes. The verifyOTPSession function in pkg/auth/local.go reads and increments the attempt counter in separate non-atomic operations, allowing concurrent requests to observe the same attempt count below the threshold and proceed past the limit check before any update is committed.
Title fastschema - TOCTOU Race Condition Bypasses OTP Attempt Limit in Account Recovery
Weaknesses CWE-367
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: TuranSec

Published:

Updated: 2026-08-10T13:14:19.784Z

Reserved: 2026-08-10T10:32:53.854Z

Link: CVE-2026-72584

cve-icon Vulnrichment

Updated: 2026-08-10T13:13:58.816Z

cve-icon NVD

Status : Deferred

Published: 2026-08-10T11:17:31.390

Modified: 2026-08-28T18:51:39.823

Link: CVE-2026-72584

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-11T14:23:39Z

Weaknesses