CVE-2023-31129 [High] | Security Vulnerability in Contiki-Ng

The Contiki-NG operating system versions 4.8 and prior can be triggered to dereference a NULL pointer in the message handling code for IPv6 router solicitiations. Contiki-NG contains an implementation of IPv6 Neighbor Discovery (ND) in the module `os/net/ipv6/uip-nd6.c`. The ND protocol includes a message type called Router Solicitation (RS), which is used to locate routers and update their address information via the SLLAO (Source Link-Layer Address Option). If the indicated source address changes, a given neighbor entry is set to the STALE state. The message handler does not check for RS messages with an SLLAO that indicates a link-layer address change that a neighbor entry can actually be created for the indicated address. The resulting pointer is used without a check, leading to the dereference of a NULL pointer of type `uip_ds6_nbr_t`. The problem has been patched in the `develop` branch of Contiki-NG, and will be included in the upcoming 4.9 release. As a workaround, users can apply Contiki-NG pull request #2271 to patch the problem directly.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.39%	0.64%	+0.25%
2	2026-01-31	0.34%	0.39%	+0.05%
3	2025-03-30	—	0.34%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.39%

0.64%

+0.25%

2026-01-31

0.34%

0.39%

+0.05%

2025-03-30

—

0.34%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.5	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	3.9	3.6	[email protected]
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.5

3.1

HIGH

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N): Service keeps running; no real outage angle.

3.9

3.6

[email protected]

9.8

3.1

CRITICAL

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

5.9

[email protected]

Affected software / configurations for CVE-2023-31129

Vendor	Product	Version	Raw CPE
contiki-ng	contiki-ng	<= 4.8	cpe:2.3:o:contiki-ng:contiki-ng::::::::

References for CVE-2023-31129

URL	Tags
https://github.com/contiki-ng/contiki-ng/pull/2271	Product
https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-x29r-5qjg-75mq	Patch Vendor Advisory

URL

CVE-2023-31129 | Contiki-NG missing NULL pointer check in IPv6 neighbor discovery

Exploit prediction scoring system (EPSS) score for CVE-2023-31129

Common vulnerability scoring system (CVSS) metrics for CVE-2023-31129

Weakness enumeration for CVE-2023-31129

Affected software / configurations for CVE-2023-31129

References for CVE-2023-31129