CVE-2026-25834
published 2026-04-01CVE-2026-25834: Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
PriorityP432medium6.5CVSS 3.1
AVNACLPRNUINSUCNILAL
EPSS
0.14%
3.4th percentile
Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
Affected
3 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | mbedtls | — | — |
| trustedfirmware | mbed_tls | — | — |
| trustedfirmware | mbed_tls | >= 3.3.0 < 3.6.6 | 3.6.6 |
CVSS provenance
nvdv3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
osv6.5MEDIUM
vendor_debian6.5MEDIUM
vendor_redhat6.5MEDIUM
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OSV
CVE-2026-25834: (Mbed TLS v3
osv·2026-04-02·CVSS 6.5
CVE-2026-25834 [MEDIUM] CVE-2026-25834: (Mbed TLS v3
(Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.)
OSV
CVE-2026-25834: Mbed TLS v3
osv·2026-04-01·CVSS 6.5
CVE-2026-25834 [MEDIUM] CVE-2026-25834: Mbed TLS v3
Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
GHSA
GHSA-8j6f-944f-8jmj: Mbed TLS v3
ghsa_unreviewed·2026-04-01
CVE-2026-25834 [MEDIUM] CWE-295 GHSA-8j6f-944f-8jmj: Mbed TLS v3
Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
Red Hat
mbedtls: Mbed TLS: Algorithm downgrade vulnerability
vendor_redhat·2026-04-01·CVSS 6.5
CVE-2026-25834 [MEDIUM] CWE-358 mbedtls: Mbed TLS: Algorithm downgrade vulnerability
mbedtls: Mbed TLS: Algorithm downgrade vulnerability
Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
A flaw was found in Mbed TLS. A remote attacker could exploit this vulnerability by performing an algorithm downgrade attack. This could lead to a reduction in the security strength of cryptographic operations, potentially allowing for information disclosure or denial of service.
Statement: Moderate: This flaw in Mbed TLS allows a remote attacker to perform an algorithm downgrade attack, which can reduce the security strength of cryptographic operations. This could potentially lead to information disclosure or denial of service. This vulnerability affects community projects such as Fedora and EPEL.
Mitigation: Mitigation for this issue is either not available or the cu
Debian
CVE-2026-25834: mbedtls - Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
vendor_debian·2026·CVSS 6.5
CVE-2026-25834 [MEDIUM] CVE-2026-25834: mbedtls - Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
Scope: local
bookworm: open
bullseye: open
forky: open
sid: open
trixie: open
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-25834 micropython: Mbed TLS: Algorithm downgrade vulnerability [fedora-all]
bugzilla·2026-04-02·CVSS 6.5
CVE-2026-25834 [MEDIUM] CVE-2026-25834 micropython: Mbed TLS: Algorithm downgrade vulnerability [fedora-all]
CVE-2026-25834 micropython: Mbed TLS: Algorithm downgrade vulnerability [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Discussion:
FEDORA-2026-d619d8d077 (micropython-1.28.0-1.fc45) has been submitted as an update to Fedora 45.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-d619d8d077
---
FEDORA-2026-52a9a687f0 (micropython-1.28.0-1.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-52a9a687f0
---
FEDORA-2026-d619d8d077 (micropython-1.28.0-1.fc45) has been pushed to the Fedora 45 stable repository.
If problem still persists, please make no
Bugzilla
CVE-2026-25834 mbedtls: Mbed TLS: Algorithm downgrade vulnerability [epel-all]
bugzilla·2026-04-02·CVSS 6.5
CVE-2026-25834 [MEDIUM] CVE-2026-25834 mbedtls: Mbed TLS: Algorithm downgrade vulnerability [epel-all]
CVE-2026-25834 mbedtls: Mbed TLS: Algorithm downgrade vulnerability [epel-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Discussion:
FEDORA-EPEL-2026-479c1d4133 (mbedtls-3.6.6-1.el10_1) has been submitted as an update to Fedora EPEL 10.1.
https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2026-479c1d4133
---
FEDORA-EPEL-2026-ba79b9dff1 (mbedtls-3.6.6-1.el10_2) has been submitted as an update to Fedora EPEL 10.2.
https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2026-ba79b9dff1
---
FEDORA-EPEL-2026-59a9d512a4 (mbedtls-3.6.6-1.el10_3) has been submitted as an update to Fedora EPEL 10.3.
https://bodhi.fe
Bugzilla
CVE-2026-25834 mbedtls: Mbed TLS: Algorithm downgrade vulnerability [fedora-all]
bugzilla·2026-04-02·CVSS 6.5
CVE-2026-25834 [MEDIUM] CVE-2026-25834 mbedtls: Mbed TLS: Algorithm downgrade vulnerability [fedora-all]
CVE-2026-25834 mbedtls: Mbed TLS: Algorithm downgrade vulnerability [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Bugzilla
CVE-2026-25834 rust-psa-crypto-sys: Mbed TLS: Algorithm downgrade vulnerability [fedora-all]
bugzilla·2026-04-02·CVSS 6.5
CVE-2026-25834 [MEDIUM] CVE-2026-25834 rust-psa-crypto-sys: Mbed TLS: Algorithm downgrade vulnerability [fedora-all]
CVE-2026-25834 rust-psa-crypto-sys: Mbed TLS: Algorithm downgrade vulnerability [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Discussion:
This package has changed maintainer in Fedora. Reassigning to the new maintainer of this component.
---
This package is not present in any active branch of Fedora.
Wiz
CVE-2026-25834 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 5.1
CVE-2026-25834 [MEDIUM] CVE-2026-25834 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-25834 :
Mbed TLS vulnerability analysis and mitigation
Mbed TLS v3.3.0 up to 3.6.5 and 4.0.0 allows Algorithm Downgrade.
Source : NVD
## 6.5
Score
Published April 1, 2026
Severity MEDIUM
CNA Score 6.5
Affected Technologies
Mbed TLS
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 5.1
Exploitation Probability (EPSS) N/A
Affected packages and libraries
cpe:2.3:a:arm:mbed_tls
mbedtls
Sources
Alpine 3.20, 3.21, 3.22, 3.23, edge Severity MEDIUM Has Fix Added at: Apr 02, 2026
Debian 11, 12, 13, 14 Severity MEDIUM No Fix Added at: Apr 05, 2026
Echo Severity MEDIUM No Fix Added at: Apr 05, 2026
Linux Severity MEDIUM Has Fix Added at: Apr 06, 2026
Linux Severity MEDIUM Has
2026-04-01
Published