CVE WatchOct 23, 2026

CVE-2026-53921

odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. Prior to version 25.12, odhcpd's DHCPv6 IA response handler w

CVSS

9.8

Critical

EPSS

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KEV

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Exploit Today

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0-100

Published: Oct 23, 2026 · Last modified: Oct 23, 2026 · CWE-121

EPSS · 30d

Not enough EPSS history yet.

Technical description

odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. Prior to version 25.12, odhcpd's DHCPv6 IA response handler writes past the end of a fixed 512-byte stack buffer (pdbuf) when a single DHCPv6 REQUEST carries enough IA options to nearly exhaust the reply space. Two independent overflow sites exist in the same call chain, both reachable from the network via a single unauthenticated UDP packet. odhcpd runs as root on OpenWrt; embedded targets often lack stack canaries and ASLR, making code execution realistic. This issue has been patched in version 25.12.

Official references

Related CVEs

CVECVSSEPSSKEVRExploitTitleMod.

CVE-2026-1158637.6 HIG

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———ConnMan through 2.0 has a stack-based buffer overflow via a DHCPv6 Reply message. This occurs in get_domains in gdhcp/client.c. It copies a fixed NS_MAXDNAME (1025) bytes from a DHCPv6 DOMAIN_LIST (option 24) value into a 1026-byte stack buffer dns_name regardless of the actual option length, then walks DNS labels with an unbounded "c += jump + 1" loop. A crafted DHCPv6 REPLY with a DOMAIN_LIST option of >= 1025 non-zero bytes makes the label walk leave the buffer and read/write '.' past its end in attacker-chosen strides. An on-link attacker can trigger this without authentication via a forged Router Advertisement (O=1) and a forged DHCPv6 REPLY matching xid/CLIENTID with a long DOMAIN_LIST. The impact is unauthenticated on-link crash of connmand (runs as root). This was introduced in bb06c47.2h CVE-2026-961857.5 HIG

44.6%

——13Stack-based buffer overflow in Microsoft Exchange Online allows an authorized attacker to execute code over a network.21h CVE-2026-94502—

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——4In EmberZNet 9.1.1 and earlier, a malformed Publish Price Matrix command can result in an out-of-bounds write potentially leading to remote code execution. These messages must come from a device that has already joined the network. Only devices supporting the Price Cluster are impacted.8h CVE-2026-85080—

27.9%

——8In EmberZNet 9.1.1 and earlier, a malformed GetGroupMembership message can result in an out-of-bounds write leading to a crash. A limited number of values can be written using this vulnerability, so no route to remote code execution was observed. These messages must come from a device that has already joined the network. Only devices supporting the Group Cluster are impacted.8h CVE-2026-85079—

22.1%

——7In EmberZNet 9.1.1 and earlier, a malformed Simple_Desc_req response can result in an out-of-bounds write potentially leading to remote code execution. This response must come from a device that has already joined the network, and the attacker must wait for a Simple_Desc_req before the attack can be performed.1d CVE-2026-11438310.0 CRI

50.7%

——15A weakness has been identified in TOTOLINK EX200 5.2.3c.7200. This impacts the function setWiFiAclAddConfig of the file /cgi-bin/cstecgi.cgi of the component wireless.so. This manipulation of the argument macAddress causes stack-based buffer overflow. The attack can be initiated remotely. The exploit has been made available to the public and could be used for attacks.1d