5.1

CVE-2026-81869: open-telemetry opentelemetry-go Improper Handling of Unicode Encoding

CVSS: 5.1v4.0MediumAwaiting analysis
AliasesUBUNTU-CVE-2026-81869DEBIAN-CVE-2026-81869GHSA-p9f8-wvj8-2fg8
Published 16-09-2026Last modified 17-09-2026
Open JSON

Vulnerability summary

CVE-2026-81869 is a medium (CVSS 5.1) Improper Handling of Unicode Encoding vulnerability in open-telemetry opentelemetry-go. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7.1% of scored vulnerabilities.

Overall risk
20/100
0100
Low · default modelHow is this calculated?
CVSS score
5.1/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.18%
0%100%
Low · +0.05 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 16-09-2026
    PublishedVulnerability first disclosed.
  2. 17-09-2026
    Last modifiedVulnerability information updated.

Description

OpenTelemetry-Go is the Go implementation of OpenTelemetry. From version 1.10.0 until 1.33.0, the sdk/trace/span.go attribute truncation path can fail to enforce AttributeValueLengthLimit for string and string-slice attributes containing the valid Unicode replacement character U+FFFD. safeTruncateValidUTF8 treats the valid replacement rune as invalid UTF-8 and returns the original input, while strings.ToValidUTF8 leaves that valid rune unchanged, so a second safeTruncate attempt can also return the oversized value. An attacker who controls span attribute content can retain values longer than the configured limit, increasing per-span memory use and weakening denial-of-service protection in the instrumented process. This issue is fixed in version 1.33.0.

CVSS metrics

6 scores · 6 sources · 1 version

EPSS trend

Probability

0.18%

Chance of exploitation in the next 30 days

Percentile

7%

Versus all other CVEs

30-day change

+0.05 pp

From 0.13% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.18%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard4 products
  • terraform-1.10All versions (No fix recorded)
  • terraform-1.11All versions (No fix recorded)
  • terraform-1.12All versions (No fix recorded)
  • terraform-1.9All versions (No fix recorded)
Debian1 product
  • golang-opentelemetry-otelAll versions (No fix recorded) | < 1.43.0-1
Go.opentelemetry.io/otel1 product
  • sdk≥ 1.10.0, < 1.33.0
Open-telemetry1 product
Ubuntu1 product
  • golang-opentelemetry-otelAll versions (No fix recorded)

5 vendors · 8 products

References

11 links
Show all 11 references