CVE-2021-43620Public exploitNetwork attack vector

Filename-extension check bypass via null-byte truncation

Published Nov 15, 2021 · Updated Aug 4, 2024

Improper input validation in fruity 0.1.0 through 0.2.0 allows attackers to bypass filename-extension checks using embedded null bytes. The NSString conversion methods and their Display, PartialEq, PartialOrd, and ToString callers pass the buffer to CStr::from_ptr, which stops at the first embedded null rather than the actual string end. Reachability requires a consuming application to validate an attacker-controlled NSString filename before using its truncated Rust conversion.

CVSS severity7.5
High
EPSS probability1.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in fruity 0.1.0 through 0.2.0 allows attackers to bypass filename-extension checks using embedded null bytes. The NSString conversion methods and their Display, PartialEq, PartialOrd, and ToString callers pass the buffer to CStr::from_ptr, which stops at the first embedded null rather than the actual string end. Reachability requires a consuming application to validate an attacker-controlled NSString filename before using its truncated Rust conversion.

The record

CVE
CVE-2021-43620
Published
Nov 15, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-20
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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