CVE-2026-18103: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') in Red Hat Red Hat Enterprise Linux 6
A buffer overflow vulnerability exists in the dhcp-server component of Red Hat Enterprise Linux 6. An attacker with network access to the OMAPI port (7911), if not secured with TSIG key authentication, can send a specially crafted lease creation request containing an overly long InfiniBand MAC address. This triggers a buffer overflow in the print_hw_addr() function, causing the dhcpd service to crash and preventing it from restarting without manual intervention, resulting in a persistent denial of service (DoS).
AI Analysis
Technical Summary
CVE-2026-18103 is a buffer overflow vulnerability in the dhcp-server of Red Hat Enterprise Linux 6. The flaw occurs in the print_hw_addr() function when processing an overly long InfiniBand MAC address in a lease creation request sent via the OMAPI port (7911). Exploitation requires network access to this port and the absence of TSIG key authentication. Successful exploitation causes the dhcpd service to crash and prevents automatic restart, leading to a persistent denial of service condition.
Potential Impact
The vulnerability allows a remote attacker with network access to the OMAPI port and without TSIG authentication to cause a persistent denial of service by crashing the dhcpd service. The service does not restart automatically after the crash, requiring manual intervention to remove the problematic lease entry and restart the service. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
To mitigate this vulnerability, configure TSIG key authentication on the OMAPI port (7911) to prevent unauthorized access. If the dhcpd service has crashed due to this flaw, manually remove the problematic InfiniBand lease entry from /var/lib/dhcpd/dhcpd.leases and then restart the dhcpd service. Note that restarting the service may temporarily interrupt DHCP services for clients. No official patch or fix is currently confirmed; check the Red Hat advisory for updates.
CVE-2026-18103: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') in Red Hat Red Hat Enterprise Linux 6
Description
A buffer overflow vulnerability exists in the dhcp-server component of Red Hat Enterprise Linux 6. An attacker with network access to the OMAPI port (7911), if not secured with TSIG key authentication, can send a specially crafted lease creation request containing an overly long InfiniBand MAC address. This triggers a buffer overflow in the print_hw_addr() function, causing the dhcpd service to crash and preventing it from restarting without manual intervention, resulting in a persistent denial of service (DoS).
CVSS v3.1
Score 4.9medium
Affected software
Red Hat
Red Hat Enterprise Linux 6
Red Hat
Red Hat Enterprise Linux 7
Red Hat
Red Hat Enterprise Linux 8
Red Hat
Red Hat Enterprise Linux 9
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-18103 is a buffer overflow vulnerability in the dhcp-server of Red Hat Enterprise Linux 6. The flaw occurs in the print_hw_addr() function when processing an overly long InfiniBand MAC address in a lease creation request sent via the OMAPI port (7911). Exploitation requires network access to this port and the absence of TSIG key authentication. Successful exploitation causes the dhcpd service to crash and prevents automatic restart, leading to a persistent denial of service condition.
Potential Impact
The vulnerability allows a remote attacker with network access to the OMAPI port and without TSIG authentication to cause a persistent denial of service by crashing the dhcpd service. The service does not restart automatically after the crash, requiring manual intervention to remove the problematic lease entry and restart the service. There is no impact on confidentiality or integrity, only availability is affected.
Mitigation Recommendations
To mitigate this vulnerability, configure TSIG key authentication on the OMAPI port (7911) to prevent unauthorized access. If the dhcpd service has crashed due to this flaw, manually remove the problematic InfiniBand lease entry from /var/lib/dhcpd/dhcpd.leases and then restart the dhcpd service. Note that restarting the service may temporarily interrupt DHCP services for clients. No official patch or fix is currently confirmed; check the Red Hat advisory for updates.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- redhat
- Date Reserved
- 2026-07-28T17:35:42.520Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Vendor Advisory Urls
- [{"url":"https://access.redhat.com/security/cve/CVE-2026-18103","vendor":"Red Hat"}]
Threat ID: 6a727538bf8831d539a7b09f
Added to database: 08/04/2026, 23:26:48 UTC
Last enriched: 08/12/2026, 15:45:10 UTC
Last updated: 09/18/2026, 02:29:13 UTC
Views: 56
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