CVE-2026-53920 odhcpd DHCPv6 Short IA_NA/IA_PD Body Stack Disclosure
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-53920?
CVE-2026-53920 is a high-severity vulnerability in openwrt odhcpd, published on 23 Oct 2026.
Official 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.
Which versions are affected by CVE-2026-53920?
How do I fix CVE-2026-53920?
No fix has been published for CVE-2026-53920 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-53920 being exploited?
There is no known exploitation of CVE-2026-53920 in the wild and no public exploit code.
Sources
Also known as GHSA-p769-5v73-pc4f.