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No exploitation reportedFix available

CVE-2026-63572

Unbounded MAC and bag-decryption iteration counts when loading PKCS#12 files

No exploitation reported by the sources we read.

  • Published2026-10-02
  • Fixed in2.7.0
  • WeaknessCWE-770

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Allocation of resources without limits in PKCS#12 keystore loading (Pkcs12Store.Load) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who can supply a PKCS#12 (PFX) file to cause a denial of service through CPU exhaustion via an iteration count close to 2^31 in the file's MacData or in the PBE parameters of an encrypted SafeContents or shrouded key bag, because the counts are taken from the file without an upper bound and the key derivation runs before the MAC or the password can be checked. A zero or negative count is covered by CVE-2026-63575. Pkcs12Utilities.ConvertToDefiniteLength is also affected.

Timeline

dates in UTC
  1. 2026-10-0208:17CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-28 09:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-63572?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-63572?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Bouncycastle bc-csharp
BranchAffectedFixed in
2.7< 2.7.02.7.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Bouncycastle bc-csharp to 2.7.0

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionnone2026-10-02
  • OpenCVESSVC decisionnone—
  • CNACVSS 4.07.1read 2026-10-28
  • NVDCVSS 3.17.5read 2026-10-28
  • CNAweakness (CWE)CWE-770read 2026-10-28
  • FIRST EPSSEPSS score0.3 %2026-10-26

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 4.0 vector
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
Published
2026-10-02
Last Modified
2026-10-28
NVD status
Analyzed

Frequently asked questions

What is CVE-2026-63572?

Allocation of resources without limits in PKCS#12 keystore loading (Pkcs12Store.Load) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who can supply a PKCS#12 (PFX) file to cause a denial of service through CPU exhaustion via an iteration count close to 2^31 in the file's MacData or in the PBE parameters of an encrypted SafeContents or shrouded key bag, because the counts are taken from the file without an upper bound and the key derivation runs before the MAC or the password can be checked. A zero or negative count is covered by CVE-2026-63575. Pkcs12Utilities.ConvertToDefiniteLength is also affected.

Is CVE-2026-63572 actively exploited?

Active exploitation of CVE-2026-63572 has not been confirmed. Its EPSS score was 0.3% on 2026-10-26, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-63572?

CVE-2026-63572 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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