CVE-2025-65821VulnerabilityPublished 10 Dec 2025Updated 11 Dec 2025

CVE-2025-65821: n/a

Source CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 30% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

AI-suggested

To mitigate CVE-2025-65821, organizations should first identify all ESP32-based devices in their environment. Immediate steps include disabling UART download mode in device firmware or hardware configurations to prevent unauthorized flash access. If disabling UART download mode is not feasible, restrict physical and network access to devices to trusted personnel and networks only. Monitor device firmware versions and apply updates as vendors release patches addressing this vulnerability. Implement network segmentation to isolate IoT devices from critical systems and sensitive data. Employ device attestation and firmware integrity checks to detect unauthorized modifications. For new deployments, prefer devices with secure boot enabled and hardened firmware configurations that disable debug interfaces by default. Additionally, conduct regular security audits and penetration tests focusing on IoT devices to detect potential exploitation attempts. Finally, maintain an inventory of affected devices and track vendor advisories for updates or patches.

Description

As UART download mode is still enabled on the ESP32 chip on which the firmware runs, an adversary can dump the flash from the device and retrieve sensitive information such as details about the current and previous Wi-Fi network from the NVS partition. Additionally, this allows the adversary to reflash the device with their own firmware which may contain malicious modifications.

Impact

For European organizations, this vulnerability poses significant risks, especially those deploying ESP32-based IoT devices in sensitive environments such as manufacturing, smart buildings, healthcare, and critical infrastructure. The ability to extract Wi-Fi credentials can lead to lateral network movement, unauthorized access to internal networks, and data exfiltration. Reflashing devices with malicious firmware can result in persistent backdoors, sabotage, or espionage. Given the widespread use of ESP32 chips in consumer and industrial IoT devices, the attack surface is broad. Confidentiality breaches could expose corporate or personal data, while integrity compromises could disrupt operations or damage trust in deployed devices. The lack of authentication and user interaction requirements lowers the barrier for exploitation, increasing the likelihood of attacks if devices are physically accessible or exposed to untrusted networks. Although no known exploits exist yet, the vulnerability's characteristics make it a critical concern for European entities relying on ESP32 devices.

CWE-1191On-Chip Debug and Test Interface With Improper Access Control (opens in a new tab)
Base weakness
The chip does not implement or does not correctly perform access control to check whether users are authorized to access internal registers and test modes through the physical debug/test interface.
Architecture and Design · Separation of Privilege
If feasible, the manufacturer should disable the JTAG interface or implement authentication and authorization for the JTAG interface. If authentication logic is added, it should be resistant to timing attacks. Security-sensitive data stored in registers, such as keys, etc. should be cleared when entering debug mode.
OWASP Cheat Sheets
Docker Security (opens in a new tab)
Third Party Javascript Management (opens in a new tab)
Virtual Patching (opens in a new tab)
OWASP ASVS 4.0.3
V1.4.4 (opens in a new tab)
V1.4.5 (opens in a new tab)
V1.10.1 (opens in a new tab)
Attack patterns
Accessing Functionality Not Properly Constrained by ACLs (opens in a new tab)
Exploiting Incorrectly Configured Access Control Security Levels (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 17 Dec 2025, 22:10 UTC

WeaknessesCWE-1191

Technical details

References

Community reviews

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