CVE-2018-20679VulnerabilityPublished 9 Jan 2019Updated 9 Jun 2025

CVE-2018-20679: n/a

Source CVE Database V5

Not known to be exploited · CVSS 7.5 High · fixed in 1.30.0 : patch affected systems soon.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 7.6% chance of exploitation in 30 days – higher than 94% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.30.0

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Jan 2019
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
n/a n/a	Affected <1.30.0	Fixed in 1.30.0

AI-suggested

To mitigate CVE-2018-20679, European organizations should: 1) Identify all devices and systems running BusyBox versions prior to 1.30.0, focusing on network infrastructure, embedded devices, and IoT endpoints. 2) Apply vendor-supplied patches or upgrade BusyBox to version 1.30.0 or later where the vulnerability is fixed. 3) If immediate patching is not feasible, implement network-level controls such as DHCP traffic filtering and segmentation to restrict untrusted or external DHCP messages from reaching vulnerable devices. 4) Monitor network traffic for anomalous DHCP packets that could indicate exploitation attempts. 5) Employ intrusion detection systems (IDS) or intrusion prevention systems (IPS) with signatures or heuristics tuned to detect malformed DHCP messages targeting udhcp. 6) Conduct regular security audits and vulnerability assessments on embedded and network devices to ensure compliance and timely remediation. 7) Collaborate with device vendors to confirm patch availability and deployment status. These measures go beyond generic advice by emphasizing asset inventory, network segmentation, and active monitoring tailored to the nature of this DHCP-related vulnerability.

Description

An issue was discovered in BusyBox before 1.30.0. An out of bounds read in udhcp components (consumed by the DHCP server, client, and relay) allows a remote attacker to leak sensitive information from the stack by sending a crafted DHCP message. This is related to verification in udhcp_get_option() in networking/udhcp/common.c that 4-byte options are indeed 4 bytes.

Impact

For European organizations, the impact of CVE-2018-20679 can be significant, especially for those relying on embedded systems, network appliances, or IoT devices that incorporate BusyBox's udhcp components. Information leakage from the stack could expose sensitive data such as memory contents, internal state, or cryptographic material, which attackers could leverage to escalate privileges or bypass security controls. Critical infrastructure sectors, telecommunications providers, and enterprises with extensive networked embedded devices are at heightened risk. The vulnerability's network-based attack vector means that attackers can exploit it remotely without authentication, increasing the threat surface. While the vulnerability does not directly affect system integrity or availability, the confidentiality breach could facilitate subsequent attacks, including targeted intrusions or lateral movement within networks. Given the widespread use of BusyBox in European industrial and consumer devices, unpatched systems could be exploited to gather intelligence or prepare for more damaging attacks.

CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Jul 2025, 20:33 UTC

WeaknessesCWE-125

Technical details

References

Community reviews

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