VulnerabilityPublished 13 Nov 2026

CVE-2026-128085: open-telemetry opentelemetry-go · Incorrect Calculation of Multi-Byte String Length

Affects open-telemetry opentelemetry-goSource CVE Database V5

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Mentioned vulnerabilities

CVE-2026-81869

Not known to be exploited · CVSS 5.3 Medium : upgrade to 1.47.0 when convenient.

Data as of 13 Nov 2026, 19:04 UTC

CVSS 3.1 base score

5.3Medium

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	5.3

Patch: Available – fixed in 1.47.0

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

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

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: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Nov 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 13 Nov 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-go and go.opentelemetry.io/otel/sdk to 1.47.0.

Affected software

Product	Affected	Fixed in
open-telemetryopentelemetry-go	Affected >=0.9.0 <1.47.0	Fixed in 1.47.0
open-telemetrygo.opentelemetry.io/otel/sdk	Affected >=1.33.0 <1.47.0	Fixed in 1.47.0
open-telemetrygo.opentelemetry.io/otel/sdk	Affected >=0.9.0 <1.47.0	Fixed in 1.47.0
open-telemetrygo.opentelemetry.io/otel/sdk	Affected >=1.35.0 <1.47.0	Fixed in 1.47.0

AI-suggested

This issue is fixed in open-telemetry opentelemetry-go version 1.47.0. Users should upgrade to version 1.47.0 or later to remediate this vulnerability. No other mitigation or workaround is indicated by the vendor advisory.

Description

CVE-2026-128085 is a vulnerability in the open-telemetry opentelemetry-go SDK affecting versions from 0.9.0, 1.33.0, and 1.35.0 up to but not including 1.47.0. The issue involves incorrect calculation of multi-byte string length where valid U+FFFD replacement characters are not counted in truncation logic. This allows attacker-controlled telemetry attributes to exceed configured memory and character limits, increasing memory retention and pipeline pressure. The vulnerability does not affect confidentiality or integrity. It is fixed in version 1.47.0.

Impact

The vulnerability allows attacker-controlled telemetry attributes to bypass configured length limits, causing increased memory usage and pipeline pressure in the telemetry processing components. There is no impact on confidentiality or integrity of data. The increased resource consumption could degrade performance or availability of telemetry processing but does not lead to data leakage or corruption.

Summary

OpenTelemetry-Go versions from SDK 1.33.0, SDK log 0.9.0, and trace 1.35.0 up to 1.47.0 contain a defect in the AttributeValueLengthLimit and WithAttributeValueLengthLimit truncation paths within sdk/internal/attrnorm, sdk/log/internal/attrnorm, and trace/auto.go. The truncation code fails to count valid U+FFFD replacement characters, introduced as an incomplete fix after CVE-2026-81869 remediation. This flaw allows telemetry attribute values dominated by these characters to exceed configured character and memory bounds in span, log-record, and auto-instrumentation trace attributes. The impact is increased memory retention and pipeline pressure from attacker-controlled telemetry attributes, without affecting confidentiality or integrity. The issue is resolved in version 1.47.0.

CWE-135Incorrect Calculation of Multi-Byte String Length (opens in a new tab)
Base weakness
The product does not correctly calculate the length of strings that can contain wide or multi-byte characters.
Implementation · Input Validation
Always verify the length of the string unit character.
Implementation · Libraries or Frameworks
Use length computing functions (e.g. strlen, wcslen, etc.) appropriately with their equivalent type (e.g.: byte, wchar_t, etc.)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-770Allocation of Resources Without Limits or Throttling (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #25
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Requirements
Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Architecture and Design
Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended.
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)
Attack patterns
XML Ping of the Death (opens in a new tab)
Exponential Data Expansion (opens in a new tab)
Serialized Data Parameter Blowup (opens in a new tab)
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (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 13 Nov 2026, 19:04 UTC

WeaknessesCWE-135, CWE-770

Technical details

References

Community reviews

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