VulnerabilityPublished 4 Feb 2026

CVE-2026-25532: espressif esp-idf · Integer Underflow

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 26 Oct 2026, 08:30 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 15% 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 26 Oct 2026.

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 update esp-idf to the patched versions 5.1.7, 5.2.7, 5.3.5, 5.4.4, or 5.5.3 depending on their current version. For devices already deployed and difficult to update, network segmentation and strict firewall rules should be applied to limit exposure of IoT devices to untrusted networks. Monitoring network traffic for anomalous or malformed EAP-WSC packets can help detect attempted exploitation. Additionally, disabling WPS functionality on devices where it is not required can reduce the attack surface. Vendors and integrators should verify firmware versions and ensure secure update mechanisms are in place. Finally, organizations should conduct security assessments of their IoT deployments to identify vulnerable devices and prioritize patching or mitigation accordingly.

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, a vulnerability exists in the WPS (Wi-Fi Protected Setup) Enrollee implementation where malformed EAP-WSC packets with truncated payloads can cause integer underflow during fragment length calculation. When processing EAP-Expanded (WSC) messages, the code computes frag_len by subtracting header sizes from the total packet length. If an attacker sends a packet where the EAP Length field covers only the header and flags but omits the expected payload (such as the 2-byte Message Length field when WPS_MSG_FLAG_LEN is set), frag_len becomes negative. This negative value is then implicitly cast to size_t when passed to wpabuf_put_data(), resulting in a very large unsigned value. 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 deploying IoT devices based on esp-idf, this vulnerability could lead to denial of service conditions, causing device outages or instability in critical infrastructure or consumer environments. Given the widespread use of Espressif chips in smart home devices, industrial sensors, and other IoT applications, disruption could affect operational continuity and service availability. While the vulnerability does not directly impact confidentiality or integrity, denial of service in IoT environments can have cascading effects, especially in sectors like manufacturing, energy, and smart city deployments prevalent in Europe. The requirement for network access means that attackers could exploit this remotely if devices are exposed or reachable through internal networks. The absence of known exploits reduces immediate risk, but the medium severity and ease of triggering the flaw through malformed packets necessitate prompt remediation to prevent potential attacks.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

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

WeaknessesCWE-191

Technical details

References

Community reviews

Related threats