CVE-2026-25508VulnerabilityPublished 4 Feb 2026

CVE-2026-25508: espressif esp-idf · Out-of-bounds Read

Affects espressif esp-idfSource CVE Database V5

Not known to be exploited · CVSS 6.3 Medium · fixed in 5.5.3 : update espressif esp-idf when convenient.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

6.3Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 5.5.3

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

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

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

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
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: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Feb 2026
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 2026-10-25.

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

Affected software

Product	Affected	Fixed in
espressifesp-idf	Affected =5.5.2 =5.4.3 =5.3.4 =5.2.6 =5.1.6	Fixed in–
GitHubespressif/esp-idf`pkg:github/espressif/esp-idf`Other threats	Affected =5.5.2 =5.4.3 =5.3.4 =5.2.6 =5.1.6	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should immediately audit their IoT device inventory to identify products using affected esp-idf versions (5.1.6, 5.2.6, 5.3.4, 5.4.3, 5.5.2). They must prioritize updating these devices to patched esp-idf versions (5.1.7, 5.2.7, 5.3.5, 5.4.4, 5.5.3) provided by Espressif. Where firmware updates are not immediately feasible, organizations should restrict physical access to BLE interfaces, especially during provisioning phases, and disable BLE provisioning if not required. Implement network segmentation and monitoring for unusual BLE activity to detect potential exploitation attempts. Device manufacturers and integrators should review provisioning workflows to minimize exposure time and consider additional authentication or authorization mechanisms during provisioning. Regular vulnerability scanning and penetration testing focusing on BLE interfaces can help identify residual risks. Finally, maintain awareness of vendor advisories for any emerging exploits or patches related to this vulnerability.

Description

ESF-IDF is the Espressif Internet of Things (IOT) Development Framework. In versions 5.5.2, 5.4.3, 5.3.4, 5.2.6, and 5.1.6, an out-of-bounds read vulnerability was reported in the BLE ATT Prepare Write handling of the BLE provisioning transport (protocomm_ble). The issue can be triggered by a remote BLE client while the device is in provisioning mode. The transport accumulated prepared-write fragments in a fixed-size buffer but incorrectly tracked the cumulative length. By sending repeated prepare write requests with overlapping offsets, a remote client could cause the reported length to exceed the allocated buffer size. This inflated length was then passed to provisioning handlers during execute-write processing, resulting in an out-of-bounds read and potential memory corruption. This issue has been patched in versions 5.5.3, 5.4.4, 5.3.5, 5.2.7, and 5.1.7.

Impact

For European organizations, the impact of this vulnerability primarily concerns IoT devices built on Espressif's esp-idf framework that utilize BLE provisioning. Exploitation could lead to memory corruption, causing device crashes or erratic behavior, which may disrupt critical IoT services or industrial control systems relying on these devices. While confidentiality is not directly compromised, the integrity and availability of devices can be affected, potentially leading to denial of service or operational interruptions. This is particularly significant for sectors with high IoT adoption such as manufacturing, smart cities, healthcare, and utilities. Disruptions in these sectors could have cascading effects on operational efficiency and safety. Since exploitation requires physical proximity to the BLE interface and user interaction to enable provisioning mode, the risk is somewhat mitigated but still relevant in environments where devices are accessible to untrusted individuals. Failure to patch could expose organizations to targeted attacks or accidental disruptions during device provisioning or maintenance.

CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Feb 2026, 18:29 UTC

WeaknessesCWE-125

Technical details

References

Community reviews

Related threats