CVE-2026-63570

Pkcs12Store.GetCertificateChain loops forever on cyclic issuer links

HIGH
7.5
CVSS Score
Published: October 2, 2026 at 07:01 AM UTC
Updated: October 28, 2026 at 01:23 PM UTC
2 products affected across 2 vendorsBc CsharpBouncy Castle for C# (bc-csharp)

Using bc-csharp by Legion of the Bouncy Castle Inc.?

Get instant alerts when new vulnerabilities affect bc-csharp - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
HIGH7.5
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

Description

Loop with unreachable exit condition in Pkcs12Store.GetCertificateChain in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who can supply a crafted PKCS#12 file to an application that loads it and requests a key entry's certificate chain to cause a denial of service, in which the call never returns and consumes CPU and memory until an OutOfMemoryException, via certificates whose issuer links form a cycle, for example two certificates whose AuthorityKeyIdentifier extensions each identify the other's public key. This happens because the chain-building loop stops only when no issuer is found or a certificate links to itself, and keeps no record of certificates already visited. The key-identifier links are followed without checking signatures.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.7.0
Affected range stops below 2.7.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-835

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card