CVE-2026-25834 | mbed TLS up to 3.6.5/4.0.0 downgrade

VDB-354754 · CVE-2026-25834 · EUVD-2026-17967 MBED TLS UP TO 3.6.5/4.0.0 DOWNGRADE HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 3.7 $0-$5k 0.85+ Summaryinfo A vulnerability categorized as problematic has been discovered in mbed TLS up to 3.6.5/4.0.0. This issue affects some unknown processing. Executing a manipulation can lead to downgrade. The identification of this vulnerability is CVE-2026-25834. The attack may be launched remotely. There is no exploit available. Detailsinfo A vulnerability classified as problematic was found in mbed TLS up to 3.6.5/4.0.0. This vulnerability affects an unknown functionality. The manipulation with an unknown input leads to a downgrade vulnerability. The CWE definition for the vulnerability is CWE-757. A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties. As an impact it is known to affect confidentiality. CVE summarizes: Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade. The advisory is available at mbed-tls.readthedocs.io. This vulnerability was named CVE-2026-25834 since 02/06/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1562.010 by the MITRE ATT&CK project. There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product. The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-17967). Productinfo Name mbed TLS Version 3.6.0 3.6.1 3.6.2 3.6.3 3.6.4 3.6.5 4.0 CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 3.7 VulDB Meta Temp Score: 3.7 VulDB Base Score: 3.7 VulDB Temp Score: 3.7 VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Downgrade CWE: CWE-757 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: no mitigation known Status: 🔍 0-Day Time: 🔒 Timelineinfo 02/06/2026 CVE reserved 04/01/2026 +53 days Advisory disclosed 04/01/2026 +0 days VulDB entry created 04/01/2026 +0 days VulDB entry last update Sourcesinfo Advisory: mbed-tls.readthedocs.io Status: Not defined CVE: CVE-2026-25834 (🔒) GCVE (CVE): GCVE-0-2026-25834 GCVE (VulDB): GCVE-100-354754 EUVD: 🔒 Entryinfo Created: 04/01/2026 20:55 Updated: 04/01/2026 22:15 Changes: 04/01/2026 20:55 (50), 04/01/2026 22:15 (1) Complete: 🔍 Cache ID: 99:58D:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸