Cyber Resilience

CVE-2026-4598

DoS in Kjur Jsrsasign ≤ 11.1.1

Public PoCDoS
Published
23 March 2026
Modified
12 August 2026
Patch / advisory
View advisory
CVSS Score v4 7.7
Click a component to see what it means
Raw vectorCVSS: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:P/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
EPSS Score 0.0055 43th percentile
Risk Priority 43 floored blend · peak EPSS

Summary

CVE-2026-4598 is a high-severity Infinite Loop (CWE-835) vulnerability in Kjur Jsrsasign. Its CVSS base score is 7.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 43th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-4598 is a denial-of-service vulnerability in versions of the jsrsasign JavaScript package prior to 11.1.1. The flaw exists in the bnModInverse function within the ext/jsbn2.js file, where the BigInteger.modInverse implementation triggers an infinite loop upon receiving zero or negative inputs, such as modInverse(0, m) or modInverse(-1, m). This CWE-835 issue carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

The vulnerability can be exploited remotely by any unauthenticated attacker with network access, requiring low complexity and no user interaction. By supplying crafted inputs to the affected function, an attacker can cause the hosting process to hang permanently, resulting in a high-impact denial of service without affecting confidentiality or integrity.

Advisories recommend updating to jsrsasign version 11.1.1 or later, which addresses the issue via a fix in commit ca5b027240287a1e71fe63019fc4400332594323 and pull request #648 on the project's GitHub repository. Further details, including a proof-of-concept, are provided in the GitHub Gist at https://gist.github.com/Kr0emer/a1bf5cd4547cc630d2dcc5e761de8264 and the Snyk advisory at https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15370938.

EU & UK References

Vulnerability Data

Versions of the package jsrsasign before 11.1.1 are vulnerable to Infinite loop via the bnModInverse function in ext/jsbn2.js when the BigInteger.modInverse implementation receives zero or negative inputs, allowing an attacker to hang the process permanently by supplying such crafted values…

more

(e.g., modInverse(0, m) or modInverse(-1, m)).

CWE(s)
CWE-835CWE-1287

Related Threats

MITRE ATT&CK Enterprise Techniques

T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
attack.mitre.org →
T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-4602Same product: Kjur Jsrsasign
CVE-2026-4599Same product: Kjur Jsrsasign
CVE-2024-21484Same product: Kjur Jsrsasign
CVE-2026-4600Same product: Kjur Jsrsasign
CVE-2026-4601Same product: Kjur Jsrsasign
CVE-2025-68137Shared CWE-835
CVE-2026-41285Shared CWE-835
CVE-2026-32873Shared CWE-835
CVE-2026-0619Shared CWE-835
CVE-2026-54417Shared CWE-835

Affected Assets

kjur
jsrsasign
≤ 11.1.1

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.1.1
  • V1.4.2
  • V2.1.1
  • V2.2.2

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation can discover unreachable loop exit conditions through static analysis, fuzzing, or execution tracing.

SI-10 Information Input Validation good match

SI-10 directly requires validation of information inputs, which structurally prevents type-validation failures from being introduced or exploitable.

SI-2 Flaw Remediation good match

Flaw remediation processes identify and correct infinite-loop defects reported from testing or operations.

SA-15 Development Process, Standards, and Tools partial match

Requiring documented development processes and secure coding standards reduces introduction of loops whose termination conditions are unreachable.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices (reviews, testing, static analysis) directly prevent introduction of infinite-loop defects.

ID.RA-01 partial match
prevents

Static analysis and vuln scanning during asset assessment can detect unreachable loop exits.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can uncover infinite-loop conditions before release.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates practices that can detect and prevent infinite-loop defects.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify loop-termination rules, indirectly reducing the weakness.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles promote defensive input handling and type enforcement at system boundaries.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly address loop termination and prevent infinite loops.

A.8.32 Change management none match
none

Change management can require review of loop logic when code is modified.

References