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highRace Conditionpublic exploit

CVE-2026-103651

CVE-2026-103651 — MISP HOTP Token Replay via Stale Session-Cached Counter Allows Second-Factor Authentication Bypass

MISP contains a vulnerability in its one-time password (OTP) authentication flow that allows replay of a consumed HOTP (paper) token and rewinding of the token counter. The HOTP verification logic compared the submitted token against a counter value that was cached in the user's session at the time the password was entered, rather than against the authoritative counter stored in the database. Because the session-cached counter is not updated after a token is successfully consumed, an attacker who holds a valid session (password already submitted) can reuse a previously burned HOTP token. The stale cached counter still matches the replayed token, granting a second successful authentication and effectively rewinding the counter state. Preconditions: - The target user has HOTP (paper token) second-factor authentication enabled. - The attacker possesses a valid session in which the password step has already been completed (the OTP step is pending). - The attacker has access to at least one HOTP token value (e.g., a paper token list). Security impact: - Bypass of the second authentication factor, allowing unauthorized access to a user's MISP account. - Corruption of the HOTP counter state, potentially invalidating subsequent legitimate tokens or enabling further replays. Affected versions: <2.5.48.

Published Updated Sources: NVD, MISP (CNA), GitHub, GitHub Security Advisory, SOCRadar CTI

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Exploit code

public exploit, none observed

EPSS

0%

ahead of 0% of scored CVEs

Affects

MISP

MISP

CVSS base

7.6

high

Remediation

The vendor's own words where we have them.

The fix replaces the session-cached HOTP counter lookup with a direct read of the authoritative counter from the database, performed under a Redis-based distributed lock scoped to the user. The token is verified against the current stored counter, the counter is incremented and persisted atomically within the locked section, and the lock is released in a finally block. Additionally, the cached OTP user session entry is deleted immediately after a successful login (for both TOTP and HOTP paths), preventing the stale session state from being reused.

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

  • Identify exposed assets running affected vendor/product/version combinations.
  • Prioritize based on EPSS, PoC availability, and external exposure.
  • Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

VendorProductVersionsStatus
MISPMISP0 to < 2.5.48Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Scope

X

Attack Complexity

High

Attack Vector

Network

Privileges Req

Low

User Interaction

None

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactSource
7.6CVSS 4.0high——MISP (CNA)

CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

What this weakness leads to

MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.

MITRE

CWE-287 · Improper Authentication

  • Read Application Data
  • Gain Privileges or Assume Identity
  • Execute Unauthorized Code or Commands

Mitigation: Use an authentication framework or library such as the OWASP ESAPI Authentication feature.::

CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

  • DoS: Resource Consumption (CPU)
  • DoS: Resource Consumption (Memory)
  • DoS: Resource Consumption (Other)
  • DoS: Crash, Exit, or Restart

Mitigation: In languages that support it, use synchronization primitives. Only wrap these around critical code to minimize the impact on performance.

Weakness & attack patterns

  • CWE-362Race Condition
  • CWE-287Improper Authentication

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

CAPEC-151 · Identity SpoofingCAPEC-57 · Utilizing REST's Trust in the System Resource to Obtain Sensitive DataCAPEC-194 · Fake the Source of DataCAPEC-22 · Exploiting Trust in ClientCAPEC-650 · Upload a Web Shell to a Web ServerCAPEC-593 · Session HijackingCAPEC-114 · Authentication AbuseCAPEC-94 · Man in the Middle AttackCAPEC-633 · Token ImpersonationCAPEC-115 · Authentication Bypass
  • T1548Abuse Elevation Control Mechanism
  • T1040Network Sniffing
  • T1185Browser Session Hijacking

Public exploit

Capability, not use: code existing is a different claim from anyone running it.

Repositories

1

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

  • Prioritize edge telemetry for network-reachable MISP.
  • Monitor for scanner or exploit-pattern traffic after 1 public PoC repositories were reported.
web/proxy/WAF logsapplication logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

  1. 2026

  2. Added · CVSS 3.1 7.6 (AV:N)

    Oct 1, 2026 · NVD

  3. Initial · CVE published

    Oct 1, 2026 · NVD

  4. Added · GHSA-28mq-63wc-4252 published (high)

    Oct 1, 2026 · GitHub Security Advisory

  5. CVE published by MITRE.

    Oct 1, 2026 · SOCRadar CTI

Source activity

Readings a source repeats on a schedule, counted rather than listed.

  • 1×CVE modified by NIST: CWE updated.Oct 1, 2026 · SOCRadar CTI
  • 1×2 times mentioned on 1 Telegram channelsOct 1, 2026 · SOCRadar CTI

References

3 on the record

Elsewhere on this site

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record1

What should defenders know first?

CVE-2026-103651 is MISP HOTP Token Replay via Stale Session-Cached Counter Allows Second-Factor Authentication Bypass, a high vulnerability affecting MISP from MISP. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-103651. Public exploit evidence is: 1 public PoC repositories reported; 0 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 7.6 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.