CVE & CISA-KEV Catalog

CVE-2026-103604

HIGH
8.7
CVSS v4
NVD

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.

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

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CVSS v4 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone

Impact

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/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

Exploit Intelligence

0.26%probability of exploitation in 30 days
16thpercentile

Low risk: more likely to be exploited than 16% of all known CVEs.

References

Other references2

Related Vulnerabilities

Other CWE-407 vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2020-27223Medium5.278%-Fix
CVE-2022-36021Medium5.560%-Fix
CVE-2021-33582High7.53.1%-Fix
CVE-2024-43485High7.53.1%-Fix
CVE-2024-43484High7.53.0%-Fix
CVE-2016-10396High7.52.9%--

Common questions

How do I fix CVE-2026-103604?

No published fix for CVE-2026-103604 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

Is CVE-2026-103604 being actively exploited?

Not that we know of. CVE-2026-103604 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.26% is the estimated probability that it will be exploited in the next 30 days. That is higher than 16% of all scored CVEs.

How severe is CVE-2026-103604?

CVE-2026-103604 has a CVSS v4 base score of 8.7, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-02.