An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). The calculations performed by mbedtls_mpi_exp_mod are not limited; thus, supplying overly large parameters could lead to denial of service when generating Diffie-Hellman key pairs.
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
IntegrityNone
AvailabilityHigh
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, VA: 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 | < 2.7.18 |
| arm | mbed_tls | ≥ 2.8.0, < 2.16.9 |
| arm | mbed_tls | ≥ 2.17.0, < 2.25.0 |
| 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
