CVE-2026-5504
Received Received - Intake
Padding Oracle Vulnerability in wolfSSL PKCS7 CBC Decryption

Publication date: 2026-04-09

Last updated on: 2026-04-29

Assigner: wolfSSL Inc.

Description
A padding oracle exists in wolfSSL's PKCS7 CBC decryption that could allow an attacker to recover plaintext through repeated decryption queries with modified ciphertext. In previous versions of wolfSSL the interior padding bytes are not validated.
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Meta Information
Published
2026-04-09
Last Modified
2026-04-29
Generated
2026-06-16
AI Q&A
2026-04-10
EPSS Evaluated
2026-06-14
NVD
CVE-2026-5504
EUVD
EUVD-2026-21235
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
wolfssl wolfssl to 5.9.0 (inc)
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-354 The product does not validate or incorrectly validates the integrity check values or "checksums" of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission.
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Executive Summary

This vulnerability is a padding oracle issue in wolfSSL's PKCS7 CBC decryption. It allows an attacker to recover plaintext data by making repeated decryption attempts with modified ciphertext. The problem arises because, in previous versions of wolfSSL, the interior padding bytes were not properly validated during decryption.

Impact Analysis

An attacker exploiting this vulnerability could recover sensitive plaintext data from encrypted communications or stored data by repeatedly querying the decryption function with altered ciphertext. This could lead to unauthorized disclosure of confidential information.

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