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CVE-2023-28771

Improper error message handling in Zyxel ZyWALL/USG series firmware versions 4.60 through 4.73, VPN series firmware versions 4.60 through 5.35, USG FLEX series firmware versions 4.60 through 5.35, and ATP series firmware versions 4.60 through 5.35, which could allow an unauthenti…

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Improper error message handling in Zyxel ZyWALL/USG series firmware versions 4.60 through 4.73, VPN series firmware versions 4.60 through 5.35, USG FLEX series firmware versions 4.60 through 5.35, and ATP series firmware versions 4.60 through 5.35, which could allow an unauthenticated attacker to execute some OS commands remotely by sending crafted packets to an affected device.
CVSS 9.8 (CRITICAL) KEV: KNOWN CATALOG

Attention and evidence

HYPE SCORE
0.0/10
REALITY · THREAT PRIORITY
9.0/10
General review priority; not probability

Evidence confidence: Exploitation recorded

Why this priority?
  • Recorded exploitation baseline: +7.00
  • Technical severity: CVSS 9.8: +1.47
  • Fresh EPSS: 99.28%: +0.50

General review priority, not probability, victim count or asset-specific risk. A range covers missing CVSS/EPSS inputs within the current evidence state.

Sources: 11 documents and public datasets.

Hype components

Headline sample (25%)
0/100
Press, 30 days (60%)
0/100
Grounded branding (15%)
0/100
HYPE TOTAL0/100

Sources and documents

Cybersecurity Dive
Press · 17 Jun 2025, 07:00 · Critical Zyxel vulnerability under active exploitation after long period of quiet - Cybersecurity Dive
The Hacker News
Press · 17 Jun 2025, 07:00 · TP-Link Router Flaw CVE-2023-33538 Under Active Exploit, CISA Issues Immediate Alert - The Hacker News
GreyNoise
Press · 16 Jun 2025, 07:00 · GreyNoise Observes Exploit Attempts Targeting Zyxel CVE-2023-28771 - GreyNoise
BleepingComputer
Press · 20 Jun 2023, 07:00 · Zyxel warns of critical command injection flaw in NAS devices - BleepingComputer
The Record from Recorded Future News
Press · 01 Jun 2023, 07:00 · Researchers warn of hackers widely exploiting bug in Zyxel hardware - The Record from Recorded Future News
See all 11 source documents
TechTarget
Press · 01 Jun 2023, 07:00 · Zyxel vulnerability under ‘widespread exploitation’ - TechTarget
BleepingComputer
Press · 31 May 2023, 07:00 · Hackers exploit critical Zyxel firewall flaw in ongoing attacks - BleepingComputer
Rapid7
Press · 31 May 2023, 07:00 · Widespread Exploitation of Zyxel Network Devices - Rapid7
The Hacker News
Press · 25 May 2023, 07:00 · Zyxel Issues Critical Security Patches for Firewall and VPN Products - The Hacker News
Arctic Wolf
Press · 24 May 2023, 07:00 · Recommendations for CVE-2023-33009 and CVE-2023-33010 - Arctic Wolf
SecurityWeek
Press · 28 Apr 2023, 07:00 · Critical Vulnerability in Zyxel Firewalls Leads to Command Execution - SecurityWeek

Score evolution

● Hype   ● Reality

Earlier evidence-support scores are retained in history; this chart shows only the current priority definition.

First record: hype 0.0 · reality 9.0 (2026-11-02 15:13). The curve appears once the score changes.

Public exploit evidence

2

Public exploit entries / repo candidates

See 2 repos with metrics
RepositoryStarsForksLanguageUpdated
getdrive/PoC7315Ruby12 Aug 2024, 07:34
benjaminhays/CVE-2023-28771-PoC308Python23 May 2023, 02:49
Evidence context and dated references

Reality is general threat/review priority, combining observed exploitation, CVSS severity and fresh EPSS. Evidence confidence is separate. This is not calibrated risk, a victim count or an asset-specific assessment. A range reflects missing numeric inputs.

Evidence in context

Confidence in exploitation evidence
Exploitation recorded
Priority basis
Recorded exploitation; CVSS 9.8; EPSS 99.3%
Attention, last 30 days
0 distinct story titles; 0 press documents; 0 publisher domains.
Technical potential
network access, no prior privileges, no user interaction.
Observed activity
Exploitation recorded in CISA KEV.
Known scale
Not quantified.
Evidence confidence basis
Trusted exploitation confirmation

Score evaluated: 2026-11-05 13:58:52.927189+00:00 · EPSS snapshot: 2026-11-05T12:03:04Z

Source event timeline
Published
25 Apr 2023, 00:00
First press mention
28 Apr 2023, 07:00
Added to the CISA KEV catalog
31 May 2023, 00:00
Latest press mention
17 Jun 2025, 07:00
Score calculated
05 Nov 2026, 13:58
PoCs on GitHub
2 repositories