CVE-2021-44429Public exploitNetwork attack vector

Daemon crash via oversized TFTP RRQ filename

Published Nov 29, 2021 · Updated Aug 4, 2024

Buffer overflow in the Vercot Serva 4.4.0 TFTP server allows remote attackers to crash the daemon via a crafted read request. Serva's RRQ handling accepts a 257-byte filename before the netascii mode field, causing the oversized field to overrun a fixed buffer. An unauthenticated UDP client with access to the TFTP service can interrupt file transfers; the public artifact demonstrates a crash, not code execution.

CVSS severity7.5
High
EPSS probability1.86%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in the Vercot Serva 4.4.0 TFTP server allows remote attackers to crash the daemon via a crafted read request. Serva's RRQ handling accepts a 257-byte filename before the netascii mode field, causing the oversized field to overrun a fixed buffer. An unauthenticated UDP client with access to the TFTP service can interrupt file transfers; the public artifact demonstrates a crash, not code execution.

The record

CVE
CVE-2021-44429
Published
Nov 29, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 29, 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:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499Endpoint Denial of Service

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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