Medium severity · published Mar 23, 2026
CVE-2026-4603
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…
5.3
CVSS
0.1%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 1% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
JS
jsrsasign ·
before 11.1.1 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-4603
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-4603
Exploit
https://gist.github.com/Kr0emer/5366b7364c4fbf7e754bc377f321e9f3
Patch
https://github.com/kjur/jsrsasign/commit/dc41d49fac4297e7a737a3ef8ebd0aa9c49ef93f
Issue Tracking
https://github.com/kjur/jsrsasign/pull/649
Third Party Advisory
https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15371176
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