An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). A NULL algorithm parameters entry looks identical to an array of REAL (size zero) and thus the certificate is considered valid. However, if the parameters do not match in any way, then the certificate should be considered invalid.
An official patch is available. Apply the patch as soon as possible.
CVSS v4.0 Metrics
Exploitability
Attack VectorNetwork
ComplexityLow
RequirementsPresent
PrivilegesNone
User InteractionNone
Threat
Exploit MaturityPoC
Vulnerable System
ConfidentialityNone
IntegrityHigh
AvailabilityNone
Subsequent System
ConfidentialityNone
IntegrityNone
AvailabilityNone
Supplemental
SafetyNegligible
AutomatableYes
RecoveryAutomatic
Value DensityConcentrated
UrgencyMedium
Patch StatusOfficial Patch
Change Log
| Date | Source | Changes | Score |
|---|
| 2026-07-21 | PoC | E: U→P | 4.6 → 6.9 |
| 2026-07-21 | nvd | AV: P→N, AC: H→L, PR: H→N, UI: A→N, VI: N→H | 0.0 → 4.6 |
| 2026-07-21 | nvd | patch: Unavailable→Official Patch | 0.0 → 0.0 |
| 2026-07-21 | cve.org | initial, patch: Unavailable | 0.0 |
Affected Software
| Vendor | Product | Version |
|---|
| arm | mbed_tls | ≥ 2.17.0, < 2.25.0 |
| arm | mbed_tls | < 2.7.18 |
| arm | mbed_tls | ≥ 2.8.0, < 2.16.9 |
| debian | debian_linux | 10.0 |
| debian | debian_linux | 9.0 |
| siemens | logo\!_cmr2020_firmware | < 2.2 |
| siemens | logo\!_cmr2040_firmware | < 2.2 |
| siemens | simatic_rtu3000c_firmware | All versions |
| siemens | simatic_rtu3030c_firmware | All versions |
| siemens | simatic_rtu3031c_firmware | All versions |
| siemens | simatic_rtu3041c_firmware | All versions |
Published: 2021-08-23
