CVE-2026-53920 Details
Description
odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. From version 17.01.0 to before version 25.12.3, odhcpd's DHCPv6 IA parser accepts an IA_NA or IA_PD option whose body is shorter than struct dhcpv6_ia_hdr, casts the option header to that full structure, and reads ia->iaid before proving that the IA body contains the IAID field. If an unauthenticated network-adjacent client places a zero-length or otherwise short IA option at the end of odhcpd's 8192-byte receive stack buffer, the IAID read crosses from data_buf into adjacent stack memory. The disclosed bytes are then reflected in the DHCPv6 reply IAID; prior ARM validation showed data_buf[8192:8196] disclosing the saved stack canary, and wider stack scans can leak ASLR-useful stack/process contents. This issue has been patched in version 25.12.3.
A vulnerability exists in the odhcpd DHCP server used by OpenWrt, affecting versions 17.01.0 prior to 25.12.3. The issue arises in the DHCPv6 IA parser, which improperly handles IA_NA and IA_PD options with bodies shorter than the required length. This flaw allows an unauthenticated network-adjacent client to craft a short IA option that overwrites adjacent stack memory, leaking sensitive information such as the stack canary and potentially useful ASLR-related data. The vulnerability has been patched in odhcpd version 25.12.3.
Users can update to odhcpd version 25.12.3 or apply a patch that validates the length of IA_NA and IA_PD options before processing them. The patch should ensure that the option length is at least 12 bytes, as specified in the relevant RFC, before reading the IAID or other fields.
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 23, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/openwrt/odhcpd/commit/719fc3abc0d7e7059871f9f572fb05ada86b8ff2 | [email protected] | Source CodeVendor |
| https://github.com/openwrt/odhcpd/commit/f2275efc72a87a95f971f159babcbadc5d241d42 | [email protected] | Source CodeVendor |
| https://github.com/openwrt/odhcpd/security/advisories/GHSA-p769-5v73-pc4f | [email protected] | AdvisoryExploitRemedyVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-125 | Out-of-bounds Read | [email protected] |
| CWE-126 | Buffer Over-read | [email protected] |
| CWE-200 | Exposure of Sensitive Information to an Unauthorized Actor | [email protected] |
| CWE-201 | Insertion of Sensitive Information Into Sent Data | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| odhcpd | >= 17.01.0, < 25.12.3 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Oct 23, 2026 | CVE Modified | CISA-ADP |
| Oct 23, 2026 | New CVE Received | [email protected] |