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🛡️ CVE-2026-4603 — jsrsasign

🟢 CVSS 2.0 — Low ⚠️ Exploit Public CWE-369 OSV
2.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

jsrsasign: Division by Zero Allows Invalid JWK Modulus to Cause Deterministic Zero Output in RSA Operations

Versions of the package jsrsasign before 11.1.1 are vulnerable to Division by zero due to the RSASetPublic/KEYUTIL parsing path in ext/rsa.js and the BigInteger.modPowInt reduction logic in ext/jsbn.js. An attacker can force RSA public-key operations (e.g., verify and encryption) to collapse to deterministic zero outputs and hide “invalid key” errors by supplying a JWK whose modulus decodes to zero.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. Rated impact: confidentiality low, integrity low, availability low.

CVSS metrics in full

The score comes from this vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Attack requirements: None — no deployment-specific condition has to hold.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: Low — limited, and the attacker does not choose what is affected.

Weakness class

CVE-2026-4603 is classified as CWE-369: Divide By Zero. A divisor derived from input is not checked for zero, terminating or destabilising the process.

Affected software

CVE-2026-4603 is recorded against 1 package.

  • jsrsasign

Timeline and source

Published on 23 March 2026 and last revised on 22 June 2026. A public exploit is known to exist, which raises the urgency of patching considerably. A vendor advisory or fix has been published. Record sourced from OSV.

References

nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
gist.github.com (Web)
github.com (Package)
security.snyk.io (Web)

Other advisories for this package

jsrsasign has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-369: Divide By Zero) in other software:

Details

Severity LOW
CVSS Score 2.0
CVSS Vector CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
CWE CWE-369
Public Exploit ⚠️ Yes
Source OSV
Published 2026-03-23
Updated 2026-08-20
Modified 2026-06-22

Affected Packages

Software From version Fixed in
jsrsasign — —

Similar Threats

Exploit Protection

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CVE-2026-4603 carries CVSS 2.0 Low rating and a public exploit already exists. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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