CVE-2026-53920
HIGH 8.7odhcpd 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.
Severe if exploited (CVSS 8.7), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.4%chance of exploitation in 30 days · 33rd percentile
Impact if exploited
8.7CVSS 4.0 · HIGH
- ConfidentialityHigh
- IntegrityNone
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
- ✓Requirements: No special attack requirements
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept
No public PoC is currently catalogued.
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Tracked sources are checked daily for recent CVEs, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.
Data snapshot:
Weakness (CWE)
- CWE-125: : Out-of-bounds Read
- CWE-126: : Buffer Over-read
- CWE-200: : Exposure of Sensitive Information to an Unauthorized Actor
- CWE-201: : Insertion of Sensitive Information Into Sent Data
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
References and research data (JSON)
All CVSS metrics
- HIGH 8.7 v4.0 · CNA Primary
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N - HIGH 8.7 v4.0 · NVD Secondary
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
References
Advisories
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-108968 EUVD · EUVD-2026-108968
Technical & other
- https://github.com/openwrt/odhcpd/security/advisories/GHSA-p769-5v73-pc4f CVE record · GitHub_M · Updated 2026-10-23T13:20:48.045Z
NVD · CVE-2026-53920 · Updated 2026-10-23T21:17:23.897 - https://github.com/openwrt/odhcpd/commit/719fc3abc0d7e7059871f9f572fb05ada86b8ff2 CVE record · GitHub_M · Updated 2026-10-23T13:20:48.045Z
NVD · CVE-2026-53920 · Updated 2026-10-23T21:17:23.897 - https://github.com/openwrt/odhcpd/commit/f2275efc72a87a95f971f159babcbadc5d241d42 CVE record · GitHub_M · Updated 2026-10-23T13:20:48.045Z
NVD · CVE-2026-53920 · Updated 2026-10-23T21:17:23.897