Medium
PKCS7 CBC Padding Oracle — Plaintext Recovery
Type: advisorySources: OSV
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.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-5504
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 3 Nov 2026, 13:15 UTC · Revision 1
Source evidence
PKCS7 CBC Padding Oracle — Plaintext Recovery
core-osv · Original sourcePublished 9 Apr 2026, 22:33 UTC
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.
osv:CVE-2026-5504
Complete source record
{
"id": "db471570c472aff2b4afc2a8196ff6e95da83f5d6d8927019955f50f41833bf1",
"url": "https://osv.dev/vulnerability/CVE-2026-5504",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "PKCS7 CBC Padding Oracle — Plaintext Recovery",
"summary": "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.",
"evidence": "osv:CVE-2026-5504",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2026-5504",
"aliases": [
"CVE-2026-5504"
],
"metrics": [
{
"type": "CVSS_V4",
"score": "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"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/wolfssl/wolfssl",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"last_affected": "922d04b3568c6428a9fb905ddee3ef5a68db3108"
}
],
"database_specific": {
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"last_affected": "5.9.0"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StandardRange"
},
{
"cpe": "cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"last_affected": "5.9.0"
}
],
"source": "CPE_RANGE"
}
]
}
}
],
"versions": [
"v5.9.0-stable",
"v5.8.4-stable",
"wolfEntropy2d",
"v5.8.2-stable",
"wolfEntropy1",
"v5.8.0-stable",
"v5.7.6-stable",
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"v4.7.0-stable",
"v4.6.0-stable",
"v4.5.0-stable",
"v4.4.0-stable",
"v4.3.0-stable",
"v4.2.0c",
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"list",
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"l",
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"v3.12.0-stable",
"v3.11.1-tls13-beta",
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"v3.10.2-stable",
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"v3.10.0-stable",
"v3.9.10b",
"v3.9.10-stable",
"v3.9.8",
"v3.9.6w",
"v3.9.6",
"v3.9.1",
"v3.9.0",
"v3.8.0",
"v3.7.3",
"v3.7.1",
"v3.7.0",
"v3.6.9",
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"v3.4.6",
"v3.4.2",
"v3.4.0",
"v3.3.3",
"v3.3.0",
"v3.2.6",
"v3.2.4",
"v3.2.0",
"v2.9.4",
"v2.9.2",
"v2.9.1",
"v0.5",
"v2.9.0",
"v2.8.6",
"v2.8.5a",
"v2.8.5",
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"v2.8.3",
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"v2.0.3",
"v2.0.2",
"v2.0rc3",
"v2.0rc2b",
"v2.0rc2",
"v2.0rc1",
"v1.9.0",
"v1.8.8.0"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-5504.json"
}
}
],
"modified": "2026-10-28T02:30:28.960976837Z",
"provider": "osv",
"references": [
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5504.json",
"https://nvd.nist.gov/vuln/detail/CVE-2026-5504",
"https://github.com/wolfSSL/wolfssl/pull/10088"
],
"provider_metadata": {
"cwe_ids": [
"CWE-354"
],
"cna_assigner": "wolfSSL",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5504.json"
}
},
"related_cves": [
{
"value": "CVE-2026-5504",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 495752,
"published_at": "2026-04-09T22:33:42.179+00:00"
}