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VulnerabilityPublished

CVE-2026-18103: Red Hat Enterprise Linux 6 · Classic Buffer Overflow

Affects Red Hat Enterprise Linux 6Source CVE Database V5

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Not known to be exploited · CVSS 4.9 Medium.

Data as of 2 Nov 2026, 22:58 UTC

CVSS 3.1 base score
4.9Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.7% chance of exploitation in 30 days – higher than 53% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 4 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Red Hat Enterprise Linux 6dhcpAffected–Fixed in–
Red Hat Enterprise Linux 7dhcpAffected–Fixed in–
Red Hat Enterprise Linux 8dhcpAffected–Fixed in–
Red Hat Enterprise Linux 9dhcpAffected–Fixed in–

AI-suggested

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.

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).

References

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