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CVE-2026-53922— odhcpd: pre-auth remote DoS via size_t underflow in dhcpv6_ia_handle_IAs (stack BOF, canary-terminated)

Quick assessment

Affected
openwrt odhcpd
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

odhcpd 是 OpenWrt 使用的 DHCPv6、DHCPv4 和路由器通告服务器。在 commit cfddd56 及更早版本中，同一链路上的未认证主机可以首先通过正常的 DHCPv6 SOLICIT 和 REQUEST 交换过程获取两个地址绑定，然后发送一个包含多个 IA_NA 选项的构造好的 RENEW 消息。之前匹配的一个 IA（IA_NA 选项）会消耗大部分响应缓冲区空间，而未匹配的一个 IA 会导致 的状态分支写入并返回一个 NOBINDING 响应，该响应长度超过剩余缓冲区空间。随后，当 函数从

CVSS 6.5 · Medium

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-53922

Vulnerability Information
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Vulnerability Title
odhcpd: pre-auth remote DoS via size_t underflow in dhcpv6_ia_handle_IAs (stack BOF, canary-terminated)
Source: CVE Program / CVE List V5
Vulnerability Description
odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. In commit cfddd56 and earlier, an unauthenticated host on the same link can first obtain two bindings through normal DHCPv6 SOLICIT and REQUEST exchanges and then send a crafted RENEW containing multiple IA_NA options. An earlier matched IA consumes most of the response buffer, an unmatched IA causes the build_ia() status branch to write and return a NOBINDING response larger than the remaining space, and a subsequent matched IA is processed after dhcpv6_ia_handle_IAs() subtracts that over-return from an unsigned size_t. The resulting underflow disables subsequent length checks and permits attacker-controlled IA_ADDR serialization beyond the 512-byte stack buffer pdbuf in handle_client_request(). The stack canary terminates odhcpd, and sustained packets can repeatedly disrupt DHCPv6 service while procd respawns the process. The observed configuration does not establish code execution.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
栈缓冲区溢出
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
openwrt odhcpd < c6792bac3905d4bf726d914e9994f6d4b98c5b57 -
openwrt openwrt < 25.12.5 -

II. Public POCs for CVE-2026-53922

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III. Intelligence Information for CVE-2026-53922

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Patches & Fixes for CVE-2026-53922 (4)

Vendor Advisories for CVE-2026-53922 (1)

Vendor Pages for CVE-2026-53922 (1)

IV. Related Vulnerabilities

Same vendor: openwrt
Same weakness: CWE-121

V. Comments for CVE-2026-53922

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