TI-2026-65845 Aliases CVE-2026-63570 GHSA-g2c8-ppvq-rq73

Pkcs12Store.GetCertificateChain loops forever on cyclic issuer links

LOW 31CWE-835Published 2026-10-02 · Updated 2026-10-02

Key facts

Attack vector: Network
Privileges required: None
User interaction: Passive
Attack complexity: Low
Attack requirements: None
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-835.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00226 13th percentileScored 2026-11-07

Fix Fixed bc-csharp (Legion of the Bouncy Castle Inc.): 2.7.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Legion of the Bouncy Castle Inc.	bc-csharp	before 2.7.0	2.7.0	Patch available	CNA

bc-csharp VendorLegion of the Bouncy Castle Inc. Affected before 2.7.0 Fixed in 2.7.0 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:bouncycastle:bc-csharp::::::::	before 2.7.0	Vulnerable	Legion of the Bouncy Castle Inc.

cpe:2.3:a:bouncycastle:bc-csharp:*:*:*:*:*:*:*:* Versions before 2.7.0 Vulnerable ·Legion of the Bouncy Castle Inc.

Remediation

Fix · CNA bc-csharp (Legion of the Bouncy Castle Inc.) Fixed in 2.7.0

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

Release · 2026-10-02
Legion of the Bouncy Castle bc-csharp 2.7.0
21 records Highest priority Priority MEDIUM 8 MEDIUM, 13 LOW
Other records, highest priority first
- TI-2026-65844 MTI/A0 DHAgreement does not validate the peer's ephemeral valuePriority MEDIUM 47
- TI-2026-66020 Unbounded HSS public key level count allows huge array allocation during signature verificationPriority MEDIUM 44
- TI-2026-66017 Unbounded ASN.1 nesting depth causes process-terminating stack overflowPriority MEDIUM 44
Show all 21 records →

Timeline

2026-10-02 Threatist record created from CVE-2026-63570
2026-10-03 Alias added: GHSA-g2c8-ppvq-rq73
2026-10-28 CVSS score added · NVD

References

Patch 2

TI-2026-65844 MTI/A0 DHAgreement does not validate the peer's ephemeral value CVSS 4.0CRITICAL 9.1
TI-2026-66020 Unbounded HSS public key level count allows huge array allocation during signature verification CVSS 4.0HIGH 8.7
TI-2026-66017 Unbounded ASN.1 nesting depth causes process-terminating stack overflow CVSS 4.0HIGH 8.7
TI-2026-65849 Unbounded allocation from OpenPGP signature and user attribute subpacket lengths CVSS 4.0HIGH 8.7
TI-2026-65843 Unbounded CMP/CRMF password-based MAC iteration count allows CPU exhaustion CVSS 4.0HIGH 8.7
TI-2026-65841 DTLS handshake reassembler allocates buffer from unchecked 24-bit length CVSS 4.0HIGH 8.7

See all 21 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences