CVE-2026-103604

Quadratic-time escaping when converting X.509 distinguished names to strings

HIGH
7.5
CVSS Score
Published: October 2, 2026 at 07:11 AM UTC
Updated: October 28, 2026 at 01:27 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 0.3%
SSVC
No known exploit

Description

Inefficient algorithmic complexity in X.509 distinguished name string conversion (X509Name.ToString and IetfUtilities.ValueToString) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote unauthenticated attacker to cause a denial of service through CPU exhaustion via a certificate, CRL, certification request or other structure whose name contains a long attribute value made up of characters that must be escaped, such as commas, or of leading or trailing spaces, because each escaping backslash was inserted into the buffer being scanned, so the work grew quadratically with the length of the value. Applications are exposed when they convert such a name to a string, for example to log or display it, or compare it with IetfUtilities.RdnAreEqual, as PKIX path validation does for directoryName name constraints.

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-407

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