CVE-2026-5504 - Vulnerability Details - OpenCVE

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.

Attack Vector Network

Attack Complexity High

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact Low

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact None

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Key SSVC decision points have not yet been added.

No data.

No data.

No data.

References

Link	Providers
https://github.com/wolfSSL/wolfssl/pull/10088

History

Thu, 09 Apr 2026 22:45:00 +0000

Type	Values Removed	Values Added
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.
Title		PKCS7 CBC Padding Oracle — Plaintext Recovery
Weaknesses		CWE-354
References		https://github.com/wolfSSL/wolfssl/pull/10088
Metrics		cvssV4_0 `{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N'}`

MITRE

Status: PUBLISHED

Assigner: wolfSSL

Published: 2026-04-09T22:33:42.179Z

Updated: 2026-04-09T22:33:42.179Z

Reserved: 2026-04-03T16:06:24.620Z

Link: CVE-2026-5504

Vulnrichment

No data.

NVD

Status : Received

Published: 2026-04-09T23:17:01.400

Modified: 2026-04-09T23:17:01.400

Link: CVE-2026-5504

Redhat

No data.

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-5504", "assignerOrgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27", "state": "PUBLISHED", "assignerShortName": "wolfSSL", "dateReserved": "2026-04-03T16:06:24.620Z", "datePublished": "2026-04-09T22:33:42.179Z", "dateUpdated": "2026-04-09T22:33:42.179Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "50d2cd11-d01a-48ed-9441-5bfce9d63b27", "shortName": "wolfSSL", "dateUpdated": "2026-04-09T22:33:42.179Z"}, "title": "PKCS7 CBC Padding Oracle \u2014 Plaintext Recovery", "problemTypes": [{"descriptions": [{"lang": "en", "cweId": "CWE-354", "description": "CWE-354 Improper validation of integrity check value", "type": "CWE"}]}], "impacts": [{"capecId": "CAPEC-463", "descriptions": [{"lang": "en", "value": "CAPEC-463 Padding Oracle Crypto Attack"}]}], "affected": [{"vendor": "wolfSSL", "product": "wolfSSL", "modules": ["PKCS7"], "programFiles": ["wolfcrypt/src/pkcs7.c"], "versions": [{"status": "affected", "version": "0", "lessThanOrEqual": "5.9.0", "versionType": "semver"}], "defaultStatus": "unaffected"}], "descriptions": [{"lang": "en", "value": "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.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "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."}]}], "references": [{"url": "https://github.com/wolfSSL/wolfssl/pull/10088"}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "MEDIUM", "baseScore": 6.3, "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N"}}], "credits": [{"lang": "en", "value": "Sunwoo Lee of Korea Institute of Energy Technology (KENTECH) for the report.", "type": "finder"}, {"lang": "en", "value": "Woohyun Choi of Korea Institute of Energy Technology (KENTECH) for the report.", "type": "finder"}, {"lang": "en", "value": "Seunghyun Yoon of Korea Institute of Energy Technology (KENTECH) for the report.", "type": "finder"}], "source": {"discovery": "EXTERNAL"}, "x_generator": {"engine": "Vulnogram 1.0.1"}}}}