VulnerabilityPublished 19 Mar 2026

CVE-2026-26933: Elastic Packetbeat · Improper Validation of Array Index

Affects Elastic PacketbeatSource CVE Database V5

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Not known to be exploited · CVSS 5.7 Medium.

Data as of 30 Oct 2026, 20:25 UTC

CVSS 3.1 base score

5.7Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
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: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 Oct 2026.

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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity 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
ElasticPacketbeat	Affected >=9.0.0 <=9.2.4 >=8.0.0 <=8.19.10	Fixed in–

AI-suggested

To mitigate CVE-2026-26933, organizations should upgrade Packetbeat to a patched version once available from Elastic. In the interim, network segmentation should be enforced to restrict access to Packetbeat monitored interfaces, ensuring that only trusted hosts can send traffic to these interfaces. Deploy network-level filtering to block malformed or suspicious packets that could trigger the vulnerability. Monitor Packetbeat logs and system metrics for signs of crashes or resource exhaustion indicative of exploitation attempts. Consider deploying Packetbeat in isolated environments or using virtualized network taps to reduce exposure. Implement strict access controls and network monitoring to detect anomalous traffic patterns. Engage with Elastic support or security advisories for updates and recommended configurations. Finally, incorporate this vulnerability into incident response plans to quickly address potential denial of service events impacting network monitoring.

Description

CVE-2026-26933 is a medium severity vulnerability in Elastic Packetbeat versions 8.0.0 and 9.0.0 caused by improper validation of array indices in multiple protocol parsers. An attacker on the same network segment or controlling routed traffic can send malformed packets that trigger out-of-bounds reads, leading to application crashes or resource exhaustion, resulting in denial of service. Exploitation does not require user interaction but does require low privileges and network access to monitored interfaces. No known exploits are currently reported in the wild. The vulnerability impacts availability but not confidentiality or integrity. Organizations using Packetbeat for network monitoring should prioritize patching or mitigating exposure to untrusted network traffic.

Impact

The primary impact of CVE-2026-26933 is denial of service against Packetbeat deployments, which can disrupt network traffic monitoring and analytics. This can impair an organization's ability to detect and respond to network threats in real time, potentially delaying incident response and increasing exposure to other attacks. Resource exhaustion or crashes may also cause loss of monitoring data and require service restarts, impacting operational continuity. Organizations relying heavily on Packetbeat for security monitoring, performance analysis, or compliance reporting may experience degraded visibility into network activity. While confidentiality and integrity of data are not directly affected, the availability impact can indirectly increase risk by reducing situational awareness. The requirement for network proximity or control over routed traffic limits the scope but does not eliminate risk in environments with exposed or poorly segmented monitoring infrastructure. This vulnerability could be leveraged in targeted attacks against critical infrastructure or enterprises with Packetbeat deployed in sensitive network segments.

CWE-129Improper Validation of Array Index (opens in a new tab)
Variant weaknessLikelihood of exploit: HighOWASP Top 10 A05:2025: Injection (opens in a new tab)
The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.
Architecture and Design · Input Validation
Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
Architecture and Design
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks…
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
Injection Prevention (opens in a new tab)
SQL Injection Prevention (opens in a new tab)
Injection Prevention in Java (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
Overflow Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

discuss.elastic.co/t/packetbeat-8-19-11-9-2-5-security-update-esa-2026-11/385533 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Mar 2026, 19:29 UTC

WeaknessesCWE-129

Technical details

References

Community reviews

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