CVE-2026-63567

See a problem?
Please try reporting it to the source first.
Source
https://cve.org/CVERecord?id=CVE-2026-63567
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63567.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-63567
Published
2026-10-02T06:58:32Z
Modified
2026-10-04T02:46:00Z
Severity
  • 8.2 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
IesEngine block-cipher mode checks padding before MAC (CBC padding oracle)
Details

Observable discrepancy in IesEngine.DecryptBlock in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker who has captured an IES or ECIES ciphertext, and who can submit modified ciphertexts for decryption under the same key pair, to recover its plaintext via a CBC padding-oracle attack, because in block-cipher mode the engine decrypts the ciphertext and removes its padding before verifying the MAC. A padding failure is therefore reported with a different error message, and without the MAC computation, compared with a MAC failure. Only applications that construct IesEngine directly with a padded block cipher, such as AES in CBC mode with PKCS#7 padding, are affected; stream-mode IES is not.

Database specific 
{
    "cna_assigner":  "bcorg",
    "cwe_ids":  [
        "CWE-203"
    ],
    "osv_generated_from":  "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63567.json"
}
References

Affected packages

Git / github.com/bcgit/bc-csharp

Affected ranges

Type
GIT
Repo
https://github.com/bcgit/bc-csharp
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
4007498b13582d90ee1eda5d9920c324428b98b3
Fixed
eaa42e1e8125b3e2e25e365c4194c7cd5932360b
Fixed
f881400b761134160ec2a05fd27c3e569453788d
Database specific
Show details 
{
    "extracted_events":  [
        {
            "introduced":  "0"
        },
        {
            "fixed":  "2.7.0"
        }
    ],
    "source":  [
        "DESCRIPTION",
        "REFERENCES"
    ]
}

Affected versions

release-1.*
release-1.8.0
release-1.8.0-RC.1
release-1.8.0-RC.2
release-1.8.0-RC.3
release-1.8.0-beta.1
release-1.8.0-beta.2
release-1.8.0-beta.3
release-1.8.0-beta.4
release-1.8.1
release-1.8.10
release-1.8.2
release-1.8.3
release-1.8.4
release-1.8.5
release-1.8.6
release-1.8.7
release-1.8.8
release-1.9.0

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-63567.json"