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UipApplication · Uip Project

CVE-2020-17438

CRITICAL · 9.8 CVSS v3.1 Published 2020-12-11
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
An issue was discovered in uIP 1.0, as used in Contiki 3.0 and other products. The code that reassembles fragmented packets fails to properly validate the total length of an incoming packet specified in its IP header, as well as the fragmentation offset value specified in the IP header. By crafting a packet with specific values of the IP header length and the fragmentation offset, attackers can write into the .bss section of the program (past the statically allocated buffer that is used for storing the fragmented data) and cause a denial of service in uip_reass() in uip.c, or possibly execute arbitrary code on some target architectures.

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

Buffer overflow in uIP 1.0's uip_reass() function allows attackers to write beyond the statically allocated buffer used for IP fragment reassembly. The vulnerability stems from missing validation of the IP header's total length and fragmentation offset values, enabling crafted packets to trigger out-of-bounds writes into the .bss section.

MitigationImplement bounds checking in uip_reass() to validate that the IP total length and fragmentation offset do not exceed the allocated buffer size before performing reassembly operations.

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

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
UipApplication
Affected:= 1.0

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
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 if uIP 1.0 is in use
    Search for uIP source files (uip.h, uip.c, uip_reass.c) or check firmware/components for uIP library inclusion. Look for the uip_reass() function definition in the codebase.
    Affected if The system uses uIP version 1.0 from the Uip Project
  2. Verify IP fragment reassembly is enabled
    Check the uIP configuration (uip-conf.h or similar) for the UIP_REASSEMBLY or UIP_FRAGMENT compilation flag being defined/enabled. Also check if the uip_reass() function is actually called from the IP input processing code.
    Affected if IP fragment reassembly feature is compiled in and active
  3. Examine uip_reass() for total length validation
    Locate the uip_reass() function in the uIP source code and inspect whether it validates that the IP header's total length value does not exceed the statically allocated reassembly buffer size (typically UIP_REASS_BUFSIZE) before copying data.
    Affected if The function lacks bounds checking on the IP total length field against the buffer size
  4. Examine uip_reass() for offset validation
    Inspect the uip_reass() function to determine if it validates that the fragmentation offset plus payload size stays within the allocated buffer boundaries.
    Affected if The function lacks validation that (fragment_offset + fragment_length) <= buffer_size
  5. Check if crafted packets can reach uip_reass()
    Verify the network interface configuration allows IP fragments to reach the uIP stack's reassembly routine. Determine if the device processes incoming IP packets with the fragmentation bit set.
    Affected if The device processes IP fragments and passes them to uip_reass() without pre-filtering

A system is affected if it uses uIP 1.0 with IP fragment reassembly enabled and the uip_reass() function lacks proper validation of IP total length and fragmentation offset values against the reassembly buffer size.

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

Implement bounds checking in uip_reass() to validate that the IP total length and fragmentation offset do not exceed the allocated buffer size before performing reassembly operations.

Fix this in Uip Scoped from the published advisory
  • Consultation8.0 h
  • Implementation4.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,840
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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-2020-17438 in production — separate from our analysis above.

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