VulnerabilityPublished 1 Apr 2026

CVE-2026-25835: PRNG

Source CVE Database V5

Not known to be exploited · CVSS 7.7 High · fixed in 3.6.6 : patch affected systems soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

7.7High

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.6.6, 1.1.0

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

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

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

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
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: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to 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 1 Apr 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 or the CVSS exploit maturity 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.

microsoft-security-response-ce

What to do

AI-suggested

1. 2. Conduct an inventory of all systems and devices using these libraries to identify affected versions. 3. Where patching is not immediately feasible, consider implementing compensating controls such as isolating vulnerable devices from critical networks or limiting their exposure. 4. Review cryptographic implementations to ensure proper use of randomness sources and consider integrating additional entropy sources if possible. 5. Employ runtime monitoring and anomaly detection to identify suspicious cryptographic behavior or unexpected network activity. 6. Engage with vendors and suppliers to confirm their remediation plans and timelines. 7. For new developments, adopt cryptographic libraries with proven secure PRNG implementations and maintain regular update cycles. 8. Educate development and security teams about the importance of secure random number generation and the risks of seed misuse. 9. Perform penetration testing focused on cryptographic weaknesses to validate the effectiveness of mitigations.

Description

To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle

Impact

The misuse of seeds in the PRNG can severely impact the security of cryptographic operations, leading to potential exposure of sensitive data, unauthorized access, and compromised communications. For organizations worldwide, this vulnerability threatens the confidentiality and integrity of data protected by Mbed TLS and TF-PSA-Crypto, especially in embedded systems, IoT devices, and applications relying on these libraries for secure communications. Attackers exploiting this flaw could predict cryptographic keys or session tokens, enabling man-in-the-middle attacks, data decryption, or impersonation. The impact extends to industries such as telecommunications, healthcare, automotive, and critical infrastructure where embedded security is paramount. Given the widespread use of these libraries in constrained environments, the vulnerability could affect a broad range of devices, increasing the attack surface. The absence of known exploits reduces immediate risk but does not eliminate the potential for future attacks. Failure to address this vulnerability could result in significant operational disruptions, data breaches, and loss of trust.

Summary

CVE-2026-25835 identifies a vulnerability in the Mbed TLS library (prior to version 3.6.6) and the TF-PSA-Crypto library (prior to version 1.1.0) related to improper handling of seeds in their Pseudo-Random Number Generators (PRNGs). PRNGs are fundamental components in cryptographic systems, generating random values used for key generation, nonces, salts, and other security-critical parameters. The misuse of seeds can degrade the entropy or predictability of the PRNG output, potentially allowing attackers to reproduce or predict random values. This undermines the confidentiality and integrity of cryptographic operations, such as TLS sessions, secure key storage, and authentication tokens. The vulnerability is particularly concerning in embedded and IoT environments where these libraries are widely deployed due to their lightweight design. Although no public exploits have been observed, the flaw represents a significant risk because it can facilitate cryptographic attacks like key recovery or session hijacking. The lack of a CVSS score indicates that the vulnerability is newly published and pending detailed assessment. The issue was reserved in early 2026 and published shortly thereafter, signaling recent discovery. The absence of patch links suggests that fixes may be forthcoming or in progress. Organizations relying on these libraries should monitor vendor advisories and prepare to apply updates promptly. Additionally, reviewing cryptographic usage and implementing defense-in-depth strategies can reduce risk exposure.

CWE-335Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG) (opens in a new tab)
Base weaknessOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product uses a Pseudo-Random Number Generator (PRNG) but does not correctly manage seeds.
OWASP Cheat Sheets
Forgot Password (opens in a new tab)
Transport Layer Protection (opens in a new tab)
User Privacy Protection (opens in a new tab)
Password Storage (opens in a new tab)
Cryptographic Storage (opens in a new tab)
OWASP ASVS 4.0.3
V2.3.1 (opens in a new tab)
V2.6.2 (opens in a new tab)
V2.7.6 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 1 Apr 2026, 18:57 UTC

WeaknessesCWE-335

Technical details

References

Community reviews

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