VulnerabilityPublished 20 Oct 2025Updated 21 Oct 2025

CVE-2025-54764: Mbed TLS · Timing Side Channel

Source CVE Database V5

Not known to be exploited · CVSS 6.2 Medium · fixed in 3.6.5 : update affected systems when convenient.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

6.2Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.6.5

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

Attack Vector: Local
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: 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: 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 20 Oct 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 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.

What to do

AI-suggested

Upgrade all affected systems to Mbed TLS version 3.6.5 or later, where the timing attack vulnerability has been addressed with constant-time implementations.
Audit application code to identify and refactor any direct calls to mbedtls_mpi_mod_inv or mbedtls_mpi_gcd functions, replacing them with secure alternatives or ensuring they are executed in constant time.
Implement strict local access controls and monitoring to prevent unauthorized users from gaining the local access required to perform timing measurements.
Employ hardware security modules (HSMs) or secure elements for cryptographic operations where feasible, as these often provide resistance against timing attacks.
Conduct regular security assessments and penetration tests focusing on side-channel vulnerabilities in cryptographic implementations.
Educate developers and security teams about side-channel risks and secure coding practices for cryptographic libraries.
Monitor vendor advisories and threat intelligence feeds for any emerging exploits or patches related to this vulnerability.

Description

Mbed TLS before 3.6.5 allows a local timing attack against certain RSA operations, and direct calls to mbedtls_mpi_mod_inv or mbedtls_mpi_gcd.

Impact

The primary impact of CVE-2025-54764 is the compromise of confidentiality through leakage of RSA private key material via timing side-channel analysis. For European organizations, this can undermine the security of encrypted communications, digital signatures, and authentication mechanisms relying on RSA keys protected by Mbed TLS. Sectors such as industrial control systems, telecommunications, healthcare devices, and IoT deployments that use Mbed TLS are particularly at risk. Successful exploitation could lead to unauthorized decryption of sensitive data, impersonation, or further lateral movement within networks. Although exploitation requires local access, the widespread use of Mbed TLS in embedded and IoT devices increases the attack surface, especially in environments with less stringent physical or local access controls. The absence of known exploits suggests limited immediate risk, but the vulnerability could be leveraged in targeted attacks against critical infrastructure or high-value assets. The impact on availability and integrity is minimal, but the breach of confidentiality alone warrants serious concern, especially for compliance with European data protection regulations such as GDPR.

CWE-208Observable Timing Discrepancy (opens in a new tab)
Base weakness
Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not.
OWASP Cheat Sheets
Error Handling (opens in a new tab)
Logging (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.4 (opens in a new tab)
V14.3.3 (opens in a new tab)
V7.3.3 (opens in a new tab)
Attack patterns
Cross-Domain Search Timing (opens in a new tab)
Application Fingerprinting (opens in a new tab)
System Footprinting (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 20 Oct 2025, 21:39 UTC

WeaknessesCWE-208

Technical details

References

Community reviews

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