# CVE-2026-21111: Samsung One UI out-of-bounds write in libsthmbc.so

Source: https://junglewise.ai/threats/cve-2026-21111-samsung-one-ui-out-of-bounds-write-in-libsthmbc-so  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-09. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-21111 · Severity: info · Published 2026-09-09

A library component in Samsung's One UI mobile operating system contains a memory corruption flaw that allows local attackers to write data beyond allocated memory boundaries. This could enable device compromise or local privilege escalation by an attacker with physical access or via a compromised application.

Technologies: [Samsung One UI](https://junglewise.ai/threats/technologies/one-ui). Vendors: [Samsung](https://junglewise.ai/threats/vendors/samsung).

## Quick answers

**Is CVE-2026-21111 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-21111 being exploited in the wild.

**How severe is CVE-2026-21111?** Informational severity, published 9 September 2026.

**Which products and versions are affected?** Samsung One UI prior to 8.5.

**Is there a fix for CVE-2026-21111?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-21111 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-21111?** Check whether you run Samsung One UI at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An out-of-bounds write vulnerability exists in the libsthmbc.so shared library component in Samsung One UI versions prior to 8.5. The vulnerability stems from insufficient input validation, allowing local attackers to write data beyond allocated memory boundaries. Attack requires local code execution (physical device access or compromised application). The vulnerability can result in memory corruption, denial of service, or potential privilege escalation. Samsung released a patch in One UI 8.5 that adds proper input validation to prevent out-of-bounds writes.

## Affected products

- Samsung One UI prior to 8.5

## Timeline

- 2026-09-09: disclosed

## References

- [https://security.samsungmobile.com/serviceWeb.smsb?year=2026&month=09](https://security.samsungmobile.com/serviceWeb.smsb?year=2026&month=09)

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