CVE-2026-103655

CVE-2026-103655 is a critical-severity vulnerability with a CVSS 4.0 base score of 9.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-294.

Key facts

Description

MISP contains a vulnerability in its two-factor authentication (TOTP) verification process that permits a valid one-time code to be accepted more than once within its time-based validity window. The issue exists in the user login flow where a TOTP code is verified as a second authentication factor. Because the system did not record whether a given TOTP period had already been consumed, the same code remained valid for its entire time window (typically 30 seconds). An attacker who captures a legitimate code during a user's login could replay it to authenticate a second session as that user. Preconditions: - The target user has TOTP-based two-factor authentication enabled. - The attacker is in a position to observe or intercept the TOTP code during a legitimate login (e.g., network-level interception, shoulder surfing, or a compromised client). - The replay must occur within the TOTP validity period. Security impact: - Unauthorized account access by replaying a captured one-time code. - Potential compromise of threat-intelligence data and administrative functions accessible to the targeted user. Affected versions: <v2.5.48.

Frequently asked questions

What is CVE-2026-103655?
MISP contains a vulnerability in its two-factor authentication (TOTP) verification process that permits a valid one-time code to be accepted more than once within its time-based validity window. The issue exists in the user login flow where a TOTP code is verified as a second authentication factor. Because the system did not record whether a given TOTP period had already been consumed, the same code remained valid for its entire time window (typically 30 seconds). An attacker who captures a legitimate code during a user's login could replay it to authenticate a second session as that user. Preconditions: - The target user has TOTP-based two-factor authentication enabled. - The attacker is in a position to observe or intercept the TOTP code during a legitimate login (e.g., network-level interception, shoulder surfing, or a compromised client). - The replay must occur within the TOTP validity period. Security impact: - Unauthorized account access by replaying a captured one-time code. - Potential compromise of threat-intelligence data and administrative functions accessible to the targeted user. Affected versions: <v2.5.48.
How severe is CVE-2026-103655?
CVE-2026-103655 has a CVSS 4.0 base score of 9.3, rated critical severity.
Is CVE-2026-103655 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (22nd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-103655?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-103655 published?
CVE-2026-103655 was published on 2026-10-01.

References

Other CWE-294 (Authentication Bypass by Capture-replay) vulnerabilities

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