basicsecurity.net
Proof, not just disclosure.
Threats / Samsung / CVE-2021-25489
CVE-2021-25489 · EUVD no mirror located · GCVE no mirror located Verified 2026-06-22

Samsung Mobile Devices vulnerability

Samsung mobile devices contain an improper input validation vulnerability in the modem interface driver that causes a format string bug, leading to kernel panic.

Verdict

Today item — known-exploited.

A format string vulnerability in Samsung mobile device modem drivers allows unauthenticated attackers to trigger kernel panics via malformed modem interface input, resulting in denial of service. Active exploitation has been observed.

CISA KEV Yes · 2023-06-293EPSS 0.00518 (verify live)4
01

Is it exploitable?

— the evidence, ranked above the score
Reported exploitation
2 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
docs.google.com ↗cisa.gov ↗Confirmed
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-06-29).
CISA KEV ↗Confirmed
Probability (EPSS)
EPSS 0.00518 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
FIRST EPSS ↗High
Severity / affected
Affected: Samsung, Mobile Devices. Confirm exact fixed builds in the vendor advisory.
NVD ↗Reported
Weakness (CWE)
Mapped to CWE-20 Improper Input Validation.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
NVD ↗Reported
WeaknessCWE-20 · Improper Input Validation
02

Who’s exploiting it?

— attribution turns risk into urgency
Attribution 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 board
1

Front door — unauthenticated access narrative 1

Attacker
I craft malformed input to the modem interface driver to trigger format string processing.
Business
Device availability is compromised as kernel panics render phones unusable until restart.
2

Keys to the kingdom — privilege/identity takeover narrative 2

Attacker
I repeatedly trigger the vulnerability to cause sustained denial of service against target devices.
Business
Customer trust erodes due to unexpected device instability and service interruptions.
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

Coverage & confidence

— what we know, and what we don’t

Established (cited)

  • KEV listing (CISA)
  • EPSS probability (FIRST)
  • 2 reported-exploitation source(s)
  • CWE weakness mapping (NVD)
  • Catalogued by Samsung Mobile (CNA)

    • Coverage gaps — stated, not hidden

  • No EUVD / GCVE mirror in feed — single-authority dependency for the identifier.
  • EPSS & exposure are time-varying; verify live at the source.
  • Threat-actor attribution not established from feed data — absence of a name is not absence of compromise.
  • No finder/reporter credit recorded in the public CVE entry — the work behind this find is unattributed.
    • Disclosure & credit2
    Catalogued by Samsung MobileCNA
    Credited with finding itNo finder named in the public CVE record — the work behind this find is unattributed.