Threats / Arm / CVE-2021-27562
CVE-2021-27562
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Arm Trusted Firmware vulnerability
Arm Trusted Firmware contains an out-of-bounds write vulnerability (CWE-787) in the non-secure processing environment handler that allows attackers to trigger system halt, overwrite secure data, or leak sensitive information.
Verdict
Today item — known-exploited.
An out-of-bounds write in Arm Trusted Firmware's NSPE handler permits non-secure code to corrupt secure memory, halt the system, or exfiltrate protected data. Active exploitation in the wild demonstrates practical attack feasibility.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
5 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03).
Probability (EPSS)
EPSS 0.03093 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Arm, Trusted Firmware. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-787 Out-of-bounds Write — weakness family: Memory safety.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I execute untrusted code in the non-secure world and invoke secure functions through the NSPE handler.
Business
System availability is compromised through denial-of-service halts triggered from unprivileged execution contexts.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I craft malicious non-secure function calls that write out-of-bounds into secure memory regions.
Business
Confidentiality and integrity of secure firmware and cryptographic keys are breached, undermining the trusted execution environment.
3
Lateral reach — past segmentation narrative 3
Attacker
I leverage the out-of-bounds write to read and exfiltrate secure data stored in protected memory.
Business
Sensitive authentication credentials and security-critical data are exposed to attackers with non-secure access.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05