CVE-2026-115485
Description
A flaw was found in the iscsiuio component of open-iscsi. The DHCPv6 option parser calls strlen() on raw network data without ensuring a NUL terminator is present, causing it to read past the buffer into heap memory. This can result in a daemon crash, a 1-byte heap overwrite, or corruption of the iSCSI initiator name. An attacker on the same network segment can trigger this by sending a crafted DHCPv6 Advertise message.
Statement
This flaw is rated Moderate because exploitation requires adjacent-network access during a narrow timing window (DHCPv6 solicit phase) on a Layer 2 segment where iscsiuio is processing DHCPv6 traffic on a hardware iSCSI offload NIC. Systems without iSCSI offload hardware are not affected. The iscsiuio daemon is socket-activated and only runs when the hardware is present and configured.
Mitigation
If DHCPv6 is not required for iscsiuio, disable DHCPv6 handling for the relevant network interface. If DHCPv6 is necessary, restrict network exposure to trusted adjacent networks and implement firewall rules to prevent forged DHCPv6 server traffic from reaching clients on shared L2 segments.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.3 | N/A | 6.3 |
| Attack Vector | Adjacent Network | N/A | Adjacent Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | Low |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
cve.org: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Red Hat CVSS v3 Score Explanation
DHCPv6 strlen on unterminated vendor option. C:L — strlen walks heap but attacker cannot observe the data. I:L — 1-byte NUL write and initiatorName corruption. A:L — unlikely to crash without ASAN; heap almost always has NUL within reach. Lowered from 8.3 per AV:A OOB precedent review.
Acknowledgements
Red Hat would like to thank Tristan Madani (Talence Security) for reporting this issue.
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