A newly disclosed vulnerability within the broadly used ISC Kea DHCP server poses a big safety threat to community infrastructure worldwide.
The flaw, designated CVE-2025-40779, permits distant attackers to crash DHCP companies with only a single maliciously crafted packet, doubtlessly disrupting community operations throughout total organizations.
The vulnerability impacts a number of variations of the Kea DHCP server, together with variations 2.7.1 via 2.7.9, 3.0.0, and three.1.0.
Key Takeaways1. CVE-2025-40779 lets attackers crash Kea DHCPv4 with one crafted unicast packet.2. Impacts Kea 2.7.1–2.7.9, 3.0.0, 3.1.0; CVSS 7.5; no workaround.3. Improve instantly.
Community directors operating these variations face speedy publicity to denial-of-service assaults that require no authentication or particular privileges to execute.
Kea DHCP Server DoS Vulnerability
The vulnerability stems from an assertion failure within the kea-dhcp4 course of when particular consumer choices work together with the subnet choice mechanism.
When a DHCPv4 consumer transmits a request containing explicit possibility mixtures, and the Kea server fails to find an acceptable subnet for that consumer, the service terminates unexpectedly with a deadly assertion error.
The assault vector is especially regarding as a result of it solely impacts unicast messages despatched on to the Kea server.
Broadcast DHCP messages, which symbolize regular community visitors, don’t set off this vulnerability. This specificity means that attackers may intentionally goal DHCP servers with exactly crafted unicast packets designed to use this weak point.
The Widespread Vulnerability Scoring System (CVSS) has assigned this flaw a rating of seven.5, categorizing it as excessive severity.
The CVSS vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H signifies that the vulnerability will be exploited remotely with low complexity, requires no privileges or person interplay, and leads to excessive availability influence.
The vulnerability was found via collaborative safety analysis, with acknowledgments going to Jochen M., Martin Dinev from Trading212, Ashwani Kumar from the Put up Graduate Institute of Medical Schooling & Analysis in Chandigarh, India, Bret Giddings from the College of Essex, and Florian Ritterhoff from Munich College of Utilized Sciences.
Threat FactorsDetailsAffected ProductsKea 2.7.1 – 2.7.93.0.03.1.0ImpactDenial of ServiceExploit PrerequisitesRemote unicast DHCPv4 request with particular consumer possibility setCVSS 3.1 Score7.5 (Excessive)
Mitigations
ISC has launched patched variations to handle this vital vulnerability. Organizations should instantly improve to Kea model 3.0.1 or 3.1.1, relying on their present deployment.
No workarounds exist for this vulnerability, making speedy patching the one viable protection technique.
Community directors ought to prioritize this replace, as DHCP companies symbolize vital infrastructure parts.
A profitable assault may render total community segments unable to acquire IP addresses, successfully creating widespread connectivity outages.
Whereas ISC stories no recognized lively exploits, the simplicity of the assault vector makes this vulnerability a pretty goal for malicious actors searching for to disrupt community operations.
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