NVD / CVE Program· CNA GitHub_M

CVE-2026-81871: OpenTelemetry-Go: Log gRPC exporter ignores env TLS certs, bypassing mTLS/pinning

Noroxi assessment

Priority: Monitor (action score 25/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.19% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
Fixed version: open-telemetry opentelemetry-go 0.21.0; azl3 azurelinux-image-tools 1.6.0-3 on Azure Linux 3.0 1.7.0-2.

Low priority for now. Upgrade to open-telemetry opentelemetry-go 0.21.0; azl3 azurelinux-image-tools 1.6.0-3 on Azure Linux 3.0 1.7.0-2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

OpenTelemetry-Go is the Go implementation of OpenTelemetry. Prior to version 0.21.0, the exporters/otlp/otlplog/otlploggrpc package loads OTEL_EXPORTER_OTLP_LOGS_CERTIFICATE, OTEL_EXPORTER_OTLP_CERTIFICATE, and related client certificate environment variables through loadEnvTLS into cfg.tlsCfg, but newGRPCDialOptions does not apply cfg.tlsCfg when creating gRPC transport credentials. The environment-only TLS path instead uses credentials.NewTLS with system roots and no configured client certificate, bypassing intended private CA pinning and mutual TLS unless the application also supplies WithTLSCredentials. A network attacker able to intercept or spoof the collector connection with a system-trusted certificate can read or alter log telemetry. This issue is fixed in version 0.21.0.

MediumCVSS 6.3 · v4.0—No exploit Fix available

Published: Sep 16, 2026
Updated: Sep 30, 2026
EPSS: 0.1% · 9th percentile
CWE: CWE-295

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 25 / 40 · 6.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.1%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · GitHub_M: 6.3; NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

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—

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Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

open-telemetry opentelemetry-go
- < 0.21.0affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:13	golang-opentelemetry-otel	from 0	—
Go	go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc	before 0.21.0	0.21.0
openSUSE:Leap 16.0	distribution	before 3.1.1-160000.4.1	3.1.1-160000.4.1
openSUSE:Leap 16.0	helm	before 4.3.0-160000.1.1	4.3.0-160000.1.1
openSUSE:Tumbleweed	alloy	before 1.20.1-1.1	1.20.1-1.1
openSUSE:Tumbleweed	distribution	before 3.1.1-8.1	3.1.1-8.1
openSUSE:Tumbleweed	helm	before 4.3.0-3.1	4.3.0-3.1
openSUSE:Tumbleweed	helm3	before 3.22.0-2.1	3.22.0-2.1
Red Hat:hummingbird:1	caddy	before 0:2.11.6-0.1.hum1	0:2.11.6-0.1.hum1
Red Hat:hummingbird:1	caddy	before 0:2.11.4-0.4.hum1	0:2.11.4-0.4.hum1
Red Hat:hummingbird:1	distribution	before 0:3.1.1-0.2.hum1	0:3.1.1-0.2.hum1
Red Hat:hummingbird:1	grafana12.4	before 0:12.4.10-0.6.hum1	0:12.4.10-0.6.hum1
Red Hat:hummingbird:1	grafana12.4	before 0:12.4.10-0.5.hum1	0:12.4.10-0.5.hum1
Red Hat:hummingbird:1	grafana13.1	before 0:13.1.6-0.2.hum1	0:13.1.6-0.2.hum1
Red Hat:hummingbird:1	grafana13.2	before 0:13.2.1-0.5.hum1	0:13.2.1-0.5.hum1
Red Hat:hummingbird:1	helm3	before 0:3.22.0-0.2.hum1	0:3.22.0-0.2.hum1
Red Hat:hummingbird:1	helm4	before 0:4.3.0-0.2.hum1	0:4.3.0-0.2.hum1
Red Hat:hummingbird:1	jaeger	before 0:2.20.0-0.9.hum1	0:2.20.0-0.9.hum1
Red Hat:hummingbird:1	loki3.6	before 0:3.6.17-0.2.hum1	0:3.6.17-0.2.hum1
Red Hat:hummingbird:1	loki3.6-canary	before 0:3.6.17-0.2.hum1	0:3.6.17-0.2.hum1
Red Hat:hummingbird:1	loki3.6-logcli	before 0:3.6.17-0.2.hum1	0:3.6.17-0.2.hum1
Red Hat:hummingbird:1	loki3.7	before 0:3.7.8-0.2.hum1	0:3.7.8-0.2.hum1
Red Hat:hummingbird:1	loki3.7-canary	before 0:3.7.8-0.2.hum1	0:3.7.8-0.2.hum1
Red Hat:hummingbird:1	loki3.7-logcli	before 0:3.7.8-0.2.hum1	0:3.7.8-0.2.hum1

Same product

open-telemetry: all records

Other highest-scoring records for the same primary product.

CVE-2026-81872OpenTelemetry-Go: BatchProcessor can busy-spin when export buffer is full
25Monitor
CVE-2026-45404OpenTelemetry-Go: Unsynchronized baggage map can panic under concurrent access
23Monitor
CVE-2026-81869OpenTelemetry-Go: UTF-8 replacement rune bypasses attribute length truncation
20Monitor

Published before and after this one in the same product

← EarlierCVE-2026-81870Sep 16, 2026 · OpenTelemetry-Go: Exporter config logging may leak endpoint URLs in info logs
8Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
open-telemetry opentelemetry-go	0.21.0 · description	Vendor (CNA)
azl3 azurelinux-image-tools 1.6.0-2 on Azure Linux 3.0	—	Microsoft (MSRC)
azl3 azurelinux-image-tools 1.6.0-3 on Azure Linux 3.0	1.7.0-2 · Release Notes	Microsoft (MSRC)
Go:go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc	0.21.0	Package registry (OSV)
opensuse:alloy	1.20.1-1.1 · openSUSE:Tumbleweed	Package registry (OSV)
opensuse:distribution	3.1.1-8.1 · openSUSE:Tumbleweed	Package registry (OSV)
opensuse:helm	4.3.0-3.1 · openSUSE:Tumbleweed	Package registry (OSV)
opensuse:helm3	3.22.0-2.1 · openSUSE:Tumbleweed	Package registry (OSV)
red hat:caddy	0:2.11.4-0.4.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:distribution	0:3.1.1-0.2.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:grafana12.4	0:12.4.10-0.5.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:grafana13.1	0:13.1.6-0.2.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:grafana13.2	0:13.2.1-0.5.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:helm3	0:3.22.0-0.2.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:helm4	0:4.3.0-0.2.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:jaeger	0:2.20.0-0.9.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:loki3.6	0:3.6.17-0.2.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:opentofu1.12	0:1.12.6-0.3.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:tempo2.10	0:2.10.8-0.3.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
red hat:tempo3.0	0:3.0.3-0.3.hum1 · Red Hat:hummingbird:1	Package registry (OSV)
suse:distribution	3.1.1-160000.4.1 · SUSE:Linux Enterprise Server 16.0	Package registry (OSV)
suse:helm	4.3.0-160000.1.1 · SUSE:Linux Micro 6.2	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

open-telemetry/opentelemetry-gocommit c65d435

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: X

Weakness class (CWE)

CWE-295 · Improper Certificate Validation

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

A certificate validation error is silently swallowed instead of terminating the connection. Often, code added for a test environment makes its way into production.

The bug in code

The whole CWE-295 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

kotlin

1override fun checkServerTrusted(chain: Array<X509Certificate>, type: String) {
2  // Left empty for the test environment
3}

Fixed

kotlin

1val client = OkHttpClient.Builder()
2  .certificatePinner(
3    CertificatePinner.Builder()
4      .add("api.sirius.example", "sha256/…")
5      .build()
6  ).build()

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

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Change log

Fix✗ → ✓Sep 28, 2026, 10:07 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/open-telemetry/opentelemetry-go/commit/c65d435b43e5e6b82310e6b18dd4cdcb8ac63a0c

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records