CVE-2026-63578
Unbounded PBE iteration count when decrypting PKCS#8 private keys
- Published
- Updated
- Reserved
- Assigned by
- bcorg
Description
Allocation of resources without limits in password-based private-key decryption (PbeUtilities.GenerateCipherParameters) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who can supply an encrypted private key, such as a PKCS#8 EncryptedPrivateKeyInfo or "ENCRYPTED PRIVATE KEY" PEM file, to cause a denial of service through CPU exhaustion via an iteration count close to 2^31, because the count is taken from the unauthenticated algorithm parameters without an upper bound and the key derivation runs before the password or the data can be checked. PKCS#5 PBES1 and PBES2 (PBKDF2), the PKCS#12 PBE algorithms and CMS password recipients (CmsPbeKey) are affected. Loading PKCS#12 files with Pkcs12Store is covered by CVE-2026-63572, and a zero or negative count with the PKCS#12 algorithms by CVE-2026-63575.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| bcorgCNA (assigner) | 4.0 | High7.1 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| NVDNVD · Analyzed | 4.0 | High7.1 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/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 |
- EPSS (exploitation in 30 days)
- 0.38% · top 68% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.1.
Weakness
Affected products
Legion of the Bouncy Castle Inc. · bc-csharp
- affected < 2.7.0
References (6)
- https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63578 (opens in a new tab)vendor-advisory
- https://github.com/bcgit/bc-csharp/commit/c00fc018fca89c077c64dd2a2a2eb00ae7d97241 (opens in a new tab)patch
- https://github.com/bcgit/bc-csharp/commit/54ea0b179ee627027829b44c45d6dd32e575bd67 (opens in a new tab)patch
- https://github.com/bcgit/bc-csharp/commit/7c0ed15f9783c9595b1a53f3900136461fd944f4 (opens in a new tab)patch
- https://github.com/bcgit/bc-csharp/commit/34a7c05f719c91c024f285c6b420d3c00f8019dd (opens in a new tab)patch
- https://github.com/bcgit/bc-csharp/commit/b57165ecb7790ecea08273b219d52d80c12990e4 (opens in a new tab)patch
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-63578)Record last updated .