Cyber Resilience

CVE-2021-47971

Public PoC
Published
16 May 2026
Modified
17 June 2026
CVSS Score v4 8.7
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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 0.0028 21th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2021-47971 is a high-severity Memory Allocation with Excessive Size Value (CWE-789) vulnerability. Its CVSS base score is 8.7 (High).

Operationally, ranked at the 21th 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

My Notes Safe 5.3 contains a denial of service vulnerability that allows attackers to crash the application by pasting excessively long character strings into note fields. Attackers can generate a payload containing 350000 repeated characters and paste it twice into…

more

a new note to trigger an application crash.

CWE(s)

Related Threats

CVEs Like This One

CVE-2023-39203Shared CWE-789
CVE-2025-23331Shared CWE-789
CVE-2026-44967Shared CWE-789
CVE-2025-12983Shared CWE-789
CVE-2024-52791Shared CWE-789
CVE-2024-37529Shared CWE-789
CVE-2026-54059Shared CWE-789
CVE-2025-26618Shared CWE-789
CVE-2025-11579Shared CWE-789
CVE-2026-47319Shared CWE-789

Affected Assets

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 SDLC practices directly prevent coding flaws that trust unvalidated size values for allocations.

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.

detects

Security testing in development can detect and block excessive allocation flaws before deployment.

prevents

Secure development lifecycle includes input validation and size checks that prevent unbounded allocations.

prevents

Application security requirements mandate bounds checking on size parameters to avoid excessive memory allocation.

prevents

Secure architecture principles require resource-limit enforcement that mitigates uncontrolled memory requests.

prevents

Secure coding standards directly prohibit allocating memory from untrusted size values without validation.

none

Capacity management monitors overall resource use but does not prevent individual allocation bugs.

References