Cyber Resilience

CVE-2026-49953

Public PoC
Published
15 June 2026
Modified
17 June 2026
CVSS Score v4 6.9
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0036 29th percentile
Risk Priority 41 floored blend · peak EPSS

Summary

CVE-2026-49953 is a medium-severity Guessable CAPTCHA (CWE-804) vulnerability in Karmainsecurity (inferred from references). Its CVSS base score is 6.9 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Password Guessing (T1110.001); ranked at the 29th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability Data

Discuz! X5.0 releases 20260320 through 20260610 contains a CAPTCHA bypass vulnerability that allows unauthenticated remote attackers to defeat challenge controls by exploiting limited complexity and predictable character sets in generated CAPTCHA images. Attackers can train a custom optical character recognition…

more

model against collected CAPTCHA samples to reliably predict challenge text, bypassing protections on login, registration, and other functionality from automated abuse.

CWE(s)
CWE-804

Related Threats

MITRE ATT&CK Enterprise Techniques

T1110.001 Password Guessing Credential Access
Adversaries with no prior knowledge of legitimate credentials within the system or environment may guess passwords to attempt access to accounts.
attack.mitre.org →
T1110.003 Password Spraying Credential Access
Adversaries may use a single or small list of commonly used passwords against many different accounts to attempt to acquire valid account credentials.
attack.mitre.org →
T1110 Brute Force Credential Access
Adversaries may use brute force techniques to gain access to accounts when passwords are unknown or when password hashes are obtained.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-70129Shared CWE-804
CVE-2025-32036Shared CWE-804
CVE-2024-23567Shared CWE-804
CVE-2025-1262Shared CWE-804
CVE-2026-27411Shared CWE-804
CVE-2026-40935Shared CWE-804
CVE-2024-23566Shared CWE-804
CVE-2024-30540Shared CWE-804
CVE-2024-31295Shared CWE-804
CVE-2025-40916Shared CWE-804

Affected Assets

Karmainsecurity
—
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure development practices directly require non-guessable CAPTCHA implementations.

PR.AA-03 partial match
prevents

Strong authentication practices include effective CAPTCHA challenges to block automated actors.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect weak CAPTCHA implementations before deployment.

A.8.26 Application security requirements partial match
prevents

Application security requirements mandate effective CAPTCHA challenges that cannot be easily bypassed by bots.

A.8.28 Secure coding partial match
prevents

Secure coding practices ensure CAPTCHA logic is resistant to automated recognition or guessing attacks.

A.8.5 Secure authentication partial match
prevents

Strong authentication mechanisms include robust CAPTCHA implementations that resist automated guessing.

References