CVE-2026-81869
CVE-2026-81869 is a medium-severity vulnerability with a CVSS 4.0 base score of 5.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-176.
Key facts
- Severity: Medium (CVSS 4.0 base score 5.1)
- EPSS exploit prediction: 0% (7th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-176
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-81869?
- 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.
- How severe is CVE-2026-81869?
- CVE-2026-81869 has a CVSS 4.0 base score of 5.1, rated medium severity.
- Is CVE-2026-81869 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-81869?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- When was CVE-2026-81869 published?
- CVE-2026-81869 was published on 2026-09-16 and last updated on 2026-09-30.
References
- https://github.com/open-telemetry/opentelemetry-go/commit/e016a78c9f5b24a1c2beeaad47686c2f2213f49a
- https://github.com/open-telemetry/opentelemetry-go/issues/5996
- https://github.com/open-telemetry/opentelemetry-go/pull/5997
- https://github.com/open-telemetry/opentelemetry-go/releases/tag/sdk/v1.33.0
- https://github.com/open-telemetry/opentelemetry-go/security/advisories/GHSA-p9f8-wvj8-2fg8
Other CWE-176 vulnerabilities
- CVE-2025-71316 — Critical (CVSS 9.8): SQLite 'sqldiff.exe' does not securely handle the way the Microsoft Windows C runtime converts Unicode characters to…
- CVE-2024-24691 — Critical (CVSS 9.6): Improper input validation in Zoom Desktop Client for Windows, Zoom VDI Client for Windows, and Zoom Meeting SDK for…
- CVE-2026-23950 — High (CVSS 8.8): node-tar,a Tar for Node.js, has a race condition vulnerability in versions up to and including 7.5.3. This is due to an…
- CVE-2026-93990 — High (CVSS 7.5): Expat before 2.8.5 fails to validate that a high surrogate in UTF-16 input is followed by a low surrogate, allowing…
- CVE-2024-43093 — High (CVSS 7.3): In shouldHideDocument of ExternalStorageProvider.java, there is a possible bypass of a file path filter designed to…
- CVE-2026-4116 — High (CVSS 7.2): Improper handling of Unicode encoding in SonicWall SMA1000 series appliances allows a remote authenticated SSLVPN user…