CVE-2026-4603Public exploit

RSA result corruption via zero-modulus JWK

Published Mar 23, 2026 · Updated Mar 23, 2026

Divide-by-zero handling in jsrsasign before 11.1.1 allows attackers to corrupt RSA public-key results via a zero-modulus JWK. RSASetPublic accepts a modulus that decodes to zero, while BigInteger.modPowInt returns after a zero divisor instead of rejecting it. Reachability requires an application to pass attacker-controlled JWK material into KEYUTIL; verification and encryption then produce deterministic zero outputs while invalid-key errors remain hidden.

CVSS severity5.3
Medium
EPSS probability0.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Divide-by-zero handling in jsrsasign before 11.1.1 allows attackers to corrupt RSA public-key results via a zero-modulus JWK. RSASetPublic accepts a modulus that decodes to zero, while BigInteger.modPowInt returns after a zero divisor instead of rejecting it. Reachability requires an application to pass attacker-controlled JWK material into KEYUTIL; verification and encryption then produce deterministic zero outputs while invalid-key errors remain hidden.

The record

CVE
CVE-2026-4603
Published
Mar 23, 2026
Updated
Mar 23, 2026
Vendor
jsrsasign project
Product
jsrsasign
Classifications
CWE-369, T1600
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 23, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 23, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <11.1.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

jsrsasign project · jsrsasignversion=0 <11.1.1

Published CVSS scores

2.0SnykCVSS: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
5.3NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
5.9SnykCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-369Divide By Zero
T1600Weaken Encryption

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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