CVE-2026-21091
HIGHCVE-2026-21091 is a high-severity (CVSS 7.8) Out-of-bounds Write vulnerability in samsung android. O3 Security detects and blocks CVE-2026-21091 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.
Out-of-bounds write in libcodec2secevrcdec.so prior to SMR Sep-2026 Release 1 allows local attackers to write out-of-bounds memory.
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-21091.
Description
Out-of-bounds write in libcodec2secevrcdec.so prior to SMR Sep-2026 Release 1 allows local attackers to write out-of-bounds memory.
Affected Products
androidsamsungDetection & mitigation playbook
Vendor / applianceDetect
Inventory every samsung android deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Remediation status
No patch has shipped for CVE-2026-21091 yet — track the samsung android advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2026-21091 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2026-21091. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-21091 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-21091 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.