Vulnerability · Published Sep 16, 2026 · Assigned by GitHub_M
CVE-2026-81869OpenTelemetry-Go: UTF-8 replacement rune bypasses attribute length truncation
Medium 5.1
In plain English
A medium-severity uncontrolled resource consumption in opentelemetry-go from open-telemetry. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 8% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:13 | golang-opentelemetry-otel | no fix listed | DEBIAN-CVE-2026-81869 |
| Debian:14 | golang-opentelemetry-otel | 1.43.0-1 | DEBIAN-CVE-2026-81869 |
| Go | go.opentelemetry.io/otel/sdk | 1.33.0 | GHSA-p9f8-wvj8-2fg8 |
| Go | go.opentelemetry.io/otel/sdk | 1.33.0 | GO-2026-6616 |
| Ubuntu:22.04:LTS | golang-opentelemetry-otel | no fix listed | UBUNTU-CVE-2026-81869 |
| Ubuntu:24.04:LTS | golang-opentelemetry-otel | no fix listed | UBUNTU-CVE-2026-81869 |
| Ubuntu:26.04:LTS | golang-opentelemetry-otel | no fix listed | UBUNTU-CVE-2026-81869 |
| Ubuntu:26.10 | golang-opentelemetry-otel | no fix listed | UBUNTU-CVE-2026-81869 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| open-telemetry | opentelemetry-go | >= 1.10.0, < 1.33.0 |
Weakness: CWE-176, CWE-400 · Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
References
- https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-p9f8-wvj8-2fg8 x_refsource_CONFIRM
- https://github.com/open-telemetry/opentelemetry-go/issues/5996 x_refsource_MISC
- https://github.com/open-telemetry/opentelemetry-go/pull/5997 x_refsource_MISC
- https://github.com/open-telemetry/opentelemetry-go/commit/e016a78c9f5b24a1c2beeaad47686c2f2213f49a x_refsource_MISC
- https://github.com/open-telemetry/opentelemetry-go/releases/tag/sdk/v1.33.0 x_refsource_MISC