Contiki-NG up to 4.5 RPL-Classic/RPL-Lite rpl-ext-header.c rpl_ext_header_srh_update addr_ptr out-of-bounds write

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CTI Interest Score
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A vulnerability was found in Contiki-NG up to 4.5. It has been rated as critical. Affected by this issue is the function rpl_ext_header_srh_update of the file rpl-ext-header.c of the component RPL-Classic/RPL-Lite. The manipulation of the argument addr_ptr with an unknown input leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-787. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Contiki-NG is an open-source, cross-platform operating system for internet of things devices. The RPL-Classic and RPL-Lite implementations in the Contiki-NG operating system versions prior to 4.6 do not validate the address pointer in the RPL source routing header This makes it possible for an attacker to cause out-of-bounds writes with packets injected into the network stack. Specifically, the problem lies in the rpl_ext_header_srh_update function in the two rpl-ext-header.c modules for RPL-Classic and RPL-Lite respectively. The addr_ptr variable is calculated using an unvalidated CMPR field value from the source routing header. An out-of-bounds write can be triggered on line 151 in os/net/routing/rpl-lite/rpl-ext-header.c and line 261 in os/net/routing/rpl-classic/rpl-ext-header.c, which contain the following memcpy call with addr_ptr as destination. The problem has been patched in Contiki-NG 4.6. Users can apply a patch out-of-band as a workaround.

The weakness was released 06/19/2021. The advisory is shared for download at This vulnerability is handled as CVE-2021-21257 since 12/22/2020. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available.

Upgrading to version 4.6 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at The best possible mitigation is suggested to be upgrading to the latest version.



CPE 2.3infoedit

CPE 2.2infoedit


VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍



VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍


Class: Memory corruption
CWE: CWE-787
ATT&CK: Unknown

Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

Price Prediction: 🔍
Current Price Estimation: 🔒


Threat Intelligenceinfoedit

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍


Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Contiki-NG 4.6


12/22/2020 CVE assigned
06/19/2021 +178 days Advisory disclosed
06/19/2021 +0 days VulDB entry created
06/21/2021 +2 days VulDB last update


Status: Confirmed
Confirmation: 🔒

CVE: CVE-2021-21257 (🔒)


Created: 06/19/2021 07:55 AM
Updated: 06/21/2021 04:32 PM
Changes: (1) source_cve_cna
Complete: 🔍


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