Timing side-channel vulnerability in AES-CBC decryption with PKCS#7 padding in Oberon PSA Crypto library

published 2025-08-29 last yr. modified 2026-10-18 22d ago also EUVD-2025-26194

cvss: 5.9; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.1%; EPSS 0.1% chance of exploitation in 30 days, percentile 0%
public exploits: 0; none known

Padding oracle attack vulnerability in Oberon microsystem AG’s Oberon PSA Crypto library in all versions since 1.0.0 and prior to 1.5.1 allows an attacker to recover plaintexts via timing measurements of AES-CBC PKCS#7 decrypt operations.

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CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: last yr. (2025-08-29)

Exploit prediction

0.09% chance of exploitation in the next 30 days, higher than 0% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
CNA	4.0	5.9	CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CNA	4.0	5.9	CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

Oberon microsystems AG Oberon PSA Crypto

Classification

Weakness

CWE-208 Observable Timing Discrepancy
CWE-327 Use of a Broken or Risky Cryptographic Algorithm

References

oberon.ch /security-advisories/cve-2025-7383/

Sources

CVE List CVE-2025-7383
NVD CVE-2025-7383

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