PatchSiren

PatchSiren cyber security CVE debrief

CVE-2021-47971 Exploit Db CVE debrief

CVE-2021-47971 is a denial-of-service vulnerability reported in My Notes Safe 5.3. According to the CVE description, an attacker can crash the application by pasting excessively long character strings into note fields; the example payload described in the record uses 350,000 repeated characters pasted twice into a new note. The NVD metadata associated with the record classifies the weakness as CWE-789 and assigns a high-severity CVSS v4.0 score, reflecting a strong availability impact.

Vendor
Exploit Db
Product
Unknown
CVSS
HIGH 8.7
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-16
Original CVE updated
2026-05-18
Advisory published
2026-05-16
Advisory updated
2026-05-18

Who should care

Anyone operating or using My Notes Safe 5.3, especially in environments where untrusted users can enter or paste content into note fields.

Technical summary

The supplied record describes an application crash caused by oversized input handling in note fields. NVD metadata lists CWE-789 and a CVSS v4.0 vector with AV:N and UI:N, indicating the issue can be triggered over the network without user interaction while primarily affecting availability. The corpus does not include a vendor fix, patch level, or mitigation details.

Defensive priority

High

Recommended defensive actions

  • Inventory any deployments of My Notes Safe 5.3 and confirm whether the affected note-entry functionality is exposed to untrusted input.
  • Restrict or disable access to note creation and editing features where feasible until an authoritative fix is identified.
  • Add input-length limits and server- or application-side validation for note fields to reduce crash risk from oversized pasted content.
  • Monitor for repeated application crashes or abnormal memory/availability events associated with note entry operations.
  • Track the linked NVD, Exploit-DB, and VulnCheck references for any fix, workaround, or updated vendor guidance.

Evidence notes

All statements above are limited to the supplied CVE description, NVD metadata, and the referenced Exploit-DB and VulnCheck links. The record publishes the CVE on 2026-05-16T16:16:22.463Z and provides no additional remediation details in the corpus.

Sources and references

Verified primary and authoritative sources

  • CVE-2021-47971 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2021-47971

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2021-47971 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2021-47971

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.