CVE-2026-53918 Details
Description
odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. Prior to version 25.12, odhcpd's DHCPv6 IA handler keeps a per-message `first` lease pointer so multiple IA options in one message reuse the same Reconfigure authentication key. A DHCPv6 REQUEST from an adjacent-network client can make the first IA set `first`, then make a later same-IAID IA fail the on-link check and free that same lease, leaving `first` dangling. A following IA in the same packet allocates a new lease and copies `first->key`, producing a 16-byte heap-use-after-free read. ASan confirms the UAF; native tracing shows the packet shape can deterministically reclaim the freed lease as the destination allocation, producing a zeroed Reconfigure key copy. The validated impact is unauthenticated adjacent-network denial of service and DHCPv6 Reconfigure/ForceRenew key confusion. Arbitrary PC control is not proven for this UAF alone. This issue has been patched in version 25.12.
A use-after-free vulnerability has been identified in the odhcpd DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt, affecting versions prior to 25.12. The issue arises in the DHCPv6 IA handler, which maintains a per-message 'first' lease pointer. This pointer can be manipulated by an adjacent-network client to create a dangling reference, leading to a heap-use-after-free condition. The vulnerability allows for an unauthenticated denial-of-service attack and confusion of the DHCPv6 Reconfigure/ForceRenew authentication keys. While the use-after-free can be exploited to read freed memory, it does not currently provide a means to execute arbitrary code.
Users can update to odhcpd version 25.12 or later, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Oct 23, 2026CISA-ADP
Assessed Oct 30, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/openwrt/odhcpd/security/advisories/GHSA-44ff-jcwh-wgc2 | CISA-ADP | AdvisoryRemedyVendor |
| https://github.com/openwrt/odhcpd/commit/26b122007030ebf192376aff8f98d428b25e2a93 | [email protected] | Source CodeVendor |
| https://github.com/openwrt/odhcpd/commit/5b283832c0a77aed20f1cc384ffc40bc768b06e9 | [email protected] | Source CodeVendor |
| https://github.com/openwrt/odhcpd/security/advisories/GHSA-44ff-jcwh-wgc2 | [email protected] | AdvisoryRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-416 | Use After Free | [email protected] |
| CWE-672 | Operation on a Resource after Expiration or Release | [email protected] |
| CWE-825 | Expired Pointer Dereference | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| odhcpd | <= 25.12 |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Oct 30, 2026 | CVE Modified | CISA-ADP |
| Oct 23, 2026 | New CVE Received | [email protected] |