VulnerabilityPublished 12 May 2026Updated 13 May 2026

CVE-2026-42348: open-telemetry opentelemetry-dotnet-contrib · Excessive Memory Allocation

Affects open-telemetry opentelemetry-dotnet-contribSource CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium : upgrade to 0.2.0-alpha.1 when convenient.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score

5.9Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 23% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.2.0-alpha.1, 0.2

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

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
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: 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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
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: 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 12 May 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 29 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

Upgrade opentelemetry-dotnet-contrib to 0.2.0-alpha.1; open-telemetry/opentelemetry-dotnet-contrib to 0.2.

Affected software

Product	Affected	Fixed in
open-telemetryopentelemetry-dotnet-contrib	Affected <0.2.0-alpha.1	Fixed in 0.2.0-alpha.1
GitHubopen-telemetry/opentelemetry-dotnet-contrib`pkg:github/open-telemetry/opentelemetry-dotnet-contrib`Other threats	Affected <0.2	Fixed in 0.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

This vulnerability is fixed in opentelemetry-dotnet-contrib version 0.2.0-alpha.1. Users should upgrade to this version or later to remediate the issue. There is no indication that the vulnerability is mitigated by configuration or network controls alone.

Description

CVE-2026-42348 is a medium severity vulnerability in the OpenTelemetry. OpAmp. Client component of opentelemetry-dotnet-contrib versions prior to 0.2.0-alpha.1. The issue involves the client allocating an unbounded buffer to read HTTP responses from the OpAMP server without an upper size limit. This can lead to memory exhaustion if the server is attacker-controlled or if a network attacker can intercept and send a very large response body. The vulnerability is fixed starting from version 0.2.

Impact

An attacker capable of controlling the OpAMP server or intercepting the network traffic can cause the vulnerable client to allocate an unbounded amount of memory by sending an extremely large HTTP response body. This can lead to memory exhaustion and potentially cause the consuming application to crash or become unresponsive, impacting availability. There is no impact on confidentiality or integrity according to the CVSS vector.

Summary

The OpenTelemetry.OpAmp.Client prior to version 0.2.0-alpha.1 does not impose an upper bound on the size of the buffer allocated to read HTTP responses from the OpAMP server. This lack of size limitation allows an attacker controlling the OpAMP server or performing a man-in-the-middle attack to cause the client to allocate excessive memory, potentially exhausting system resources. This vulnerability is classified under CWE-789 (Memory Allocation with Excessive Size Value). The issue has a CVSS v3.1 base score of 5.9, reflecting a network attack vector with high complexity and no privileges required, resulting in availability impact only. The vulnerability is resolved in version 0.2.0-alpha.1 of the opentelemetry-dotnet-contrib package.

CWE-789Memory Allocation with Excessive Size Value (opens in a new tab)
Variant weakness
The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.
Implementation · Architecture and Design
Perform adequate input validation against any value that influences the amount of memory that is allocated. Define an appropriate strategy for handling requests that exceed the limit, and consider supporting a configuration option so that the administrator can extend the amount of memory to be used if necessary.
Operation
Run your program using system-provided resource limits for memory. This might still cause the program to crash or exit, but the impact to the rest of the system will be minimized.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V8.1.4 (opens in a new tab)
V13.4.1 (opens in a new tab)
V11.1.4 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 20 May 2026, 19:08 UTC

WeaknessesCWE-789

Technical details

References

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