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Classic Buffer OverflowWeakness · CWE-120

CVE-2024-13503

CRITICAL · 9.5 CVSS v4.0 Published 2025-01-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') vulnerability in Newtec NTC2218, NTC2250, NTC2299 on Linux, PowerPC, ARM (Updating signaling process in the swdownload binary modules) allows Local Execution of Code, Remote Code Inclusion. This issue affects NTC2218, NTC2250, NTC2299: from 1.0.1.1 through 2.2.6.19. The issue is both present on the PowerPC versions of the modem and the ARM versions. A stack buffer buffer overflow in the swdownload binary allows attackers to execute arbitrary code. The parse_INFO function uses an unrestricted `sscanf` to read a string of an incoming network packet into a statically sized buffer.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A stack-based buffer overflow exists in the swdownload binary's parse_INFO function on Newtec NTC2218, NTC2250, and NTC2299 modems. The function uses an unbounded sscanf to copy data from incoming network packets into a fixed-size stack buffer without size validation, allowing an attacker to overwrite return addresses and execute arbitrary code.

MitigationIsolate affected modems from untrusted networks immediately; contact Newtec for patched firmware and apply updates when available; implement network monitoring for exploitation attempts.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify modem model
    Access the modem's web interface, CLI, or SNMP interface and retrieve the exact model number (NTC2218, NTC2250, or NTC2299)
    Affected if The model is one of NTC2218, NTC2250, or NTC2299
  2. Check firmware version
    Retrieve the firmware version from the modem's administration interface or via CLI command (often 'show version' or similar)
    Affected if The firmware version has not been patched by the vendor; compare against any released security patches for CVE-2024-13503
  3. Locate swdownload binary
    Access the modem's filesystem via CLI, SSH, or diagnostic mode and locate the 'swdownload' binary (typically in /usr/bin, /sbin, or similar system paths)
    Affected if The swdownload binary exists on the device and is a version containing the parse_INFO function
  4. Verify parse_INFO function exists
    Use strings, objdump, or similar tooling on the swdownload binary to locate the parse_INFO function, or check for presence of sscanf calls without size limits in the function disassembly
    Affected if The parse_INFO function uses unbounded sscanf for incoming network packet data
  5. Assess network exposure
    Check firewall rules, NAT configuration, and network ACLs to determine if the swdownload service (typically listens on network ports for firmware updates) is accessible from untrusted networks
    Affected if The swdownload service is reachable from external/untrusted networks without proper segmentation

The environment is affected if it uses a Newtec NTC2218, NTC2250, or NTC2299 modem with unpatched firmware where the swdownload binary with the vulnerable parse_INFO function is network-accessible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Isolate affected modems from untrusted networks immediately; contact Newtec for patched firmware and apply updates when available; implement network monitoring for exploitation attempts.

Have this fixed Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA4.0 h
40.0 hours of engineering $7,000
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-13503 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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