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TI-2026-79902 Aliases CVE-2026-53920

odhcpd DHCPv6 Short IA_NA/IA_PD Body Stack Disclosure

Priority MEDIUM 44CWE-125Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Information disclosure
Confidentiality · integrity · availability
High · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-125 and the CVSS impact.

Summary

odhcpd, the DHCPv6, DHCPv4 and router-advertisement server used by OpenWrt, versions from 17.01.0 to before 25.12.3, reads the IAID field of a DHCPv6 IA_NA or IA_PD option before checking that the option body is long enough to contain it. An unauthenticated client on the local network can send a zero-length or short IA option so that the read crosses past the 8192-byte receive buffer into adjacent stack memory. The bytes read are echoed in the DHCPv6 reply IAID, which can expose the stack canary and other stack contents useful for defeating ASLR. The weakness is classified as CWE-125, CWE-126, CWE-200 and CWE-201.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00395 33rd percentileScored 2026-11-07
Fix Fixed odhcpd (openwrt): 25.12.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
openwrtodhcpd17.01.0 to before 25.12.325.12.3Patch availableCNA
  • odhcpd Vendoropenwrt Affected 17.01.0 to before 25.12.3 Fixed in 25.12.3 Patch available CNA

Remediation

Upgrade odhcpd to version 25.12.3, which fixes the issue.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

  • Fix · CNA odhcpd (openwrt) Fixed in 25.12.3

Timeline

  1. 2026-10-23 Threatist record created from CVE-2026-53920
  2. 2026-10-23 CISA SSVC decision points changed

References

Other 3

  • TI-2026-79903 Stack buffer overflow in odhcpd DHCPv6 IA reply handling CVSS 3.1CRITICAL 9.8
  • TI-2024-13053 Improper input validation in MediaTek MT6890, MT7915, MT7916, MT7981, MT7986 CVSS 3.1CRITICAL 9.8
  • TI-2026-79901 Use-after-free in odhcpd DHCPv6 IA handling CVSS 4.0HIGH 8.8
  • TI-2026-48502 OpenWrt luci-app-bmx7 Path Traversal via bmx7-info CVSS 4.0HIGH 8.7
  • TI-2026-44407 luci-app-banip Log Monitor IP Extraction Bypass CVSS 4.0HIGH 8.7
  • TI-2026-51067 luci-app-openvpn Path Traversal RCE via instance_name2 CVSS 4.0CRITICAL 9.4
See all 168 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences