CVE-2026-55606
odhcpd: Stack buffer overread via DUID length endianness mismatch in memcmp()
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CVSS v3.1 (listed by NVD)
6.5
MEDIUM
Scored by github.com (not yet scored by NVD)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
CVSS v4.0 (listed by NVD)
—
Not scored
CVSS (listed by CVE.org)
6.5
MEDIUM
Scored by CNA (GitHub_M) · v3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
EPSS exploit probability
0.5%
Percentile 40.0%
as of 2026-10-24
CISA KEV
—
Not listed
Attack conditions and impact
Derived from the CNA (via NVD) CVSS 3.1 vector
NetworkNo authNo interaction
Confidentiality LIntegrity NAvailability L
This vulnerability may be exploitable over the internet without authentication or user interaction.
| Metric | Value | Meaning |
|---|---|---|
| Attack vector AV | N | Network |
| Attack complexity AC | L | Low (easy) |
| Privileges required PR | N | None |
| User interaction UI | N | None |
| Scope S | U | Unchanged |
| Confidentiality C | L | Low |
| Integrity I | N | None |
| Availability A | L | Low |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
Description
NVD
odhcpd is the DHCPv6, DHCPv4, and router-advertisement server used by OpenWrt. In versions 25.12 and prior, odhcpd's DHCPv6 self-loop detection at dhcpv6.c:720 uses a network-byte-order DUID length value directly as the memcmp() size parameter. On little-endian hosts, this causes memcmp() to read far beyond the stack buffer — a single unauthenticated DHCPv6 packet triggers a 2560-byte overread from a 128-byte buffer. At time of publication, there are no publicly available patches.
CVSS assessments
| Provider | Version | Score | Vector |
|---|---|---|---|
| NVD / [email protected] (Secondary) | 3.1 | 6.5 MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L |
| CNA / GitHub_M | 3.1 | 6.5 MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L |
Affected products and packages
CNA (CVE.org)
| Vendor | Product | Versions |
|---|---|---|
| openwrt | odhcpd | affected: <= 25.12 |
Linux distribution status
References (4)
- https://github.com/openwrt/odhcpd/commit/6907f28f9ddeef9f69f5ee10bbc9ba8adc0ef57f NVD, CNA x_refsource_MISC
- https://github.com/openwrt/odhcpd/commit/ed38cffa927d5fd450d20bfd3f7fb8d8e8fff301 NVD, CNA x_refsource_MISC
- https://github.com/openwrt/odhcpd/pull/401 NVD, CNA x_refsource_MISC
- https://github.com/openwrt/odhcpd/security/advisories/GHSA-x8x4-7gvf-gp45 NVD, CNA x_refsource_CONFIRM