How severe is CVE-2026-4603?

CVE-2026-4603 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2026-4603 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-4603?

CVE-2026-4603 affects Kjur Jsrsasign. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-4603?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-4603 have an EU (EUVD) identifier?

Yes. CVE-2026-4603 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-14380.

When was CVE-2026-4603 published?

CVE-2026-4603 was published on 2026-03-23 and last updated on 2026-06-22.

CVE-2026-4603

CVE-2026-4603 is a medium-severity vulnerability in Kjur Jsrsasign with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-369.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v4: 2.0
EPSS exploit prediction: 0% (1st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-14380
Weakness: CWE-369
Affected product: Kjur Jsrsasign
Published: 2026-03-23
Last modified: 2026-06-22

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.

Frequently asked questions

What is 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 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 severe is CVE-2026-4603?: CVE-2026-4603 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2026-4603 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-4603?: CVE-2026-4603 affects Kjur Jsrsasign. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-4603?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-4603 have an EU (EUVD) identifier?: Yes. CVE-2026-4603 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-14380.
When was CVE-2026-4603 published?: CVE-2026-4603 was published on 2026-03-23 and last updated on 2026-06-22.

References

Affected products (1)

cpe:2.3:a:kjur:jsrsasign:*:*:*:*:*:node.js:*:*

More vulnerabilities in Kjur Jsrsasign

CVE-2020-14968 — Critical (CVSS 9.8): An issue was discovered in the jsrsasign package before 8.0.17 for Node.js. Its RSASSA-PSS (RSA-PSS) implementation…
CVE-2020-14967 — Critical (CVSS 9.8): An issue was discovered in the jsrsasign package before 8.0.18 for Node.js. Its RSA PKCS1 v1.5 decryption…
CVE-2026-4599 — Critical (CVSS 9.1): Versions of the package jsrsasign from 7.0.0 and before 11.1.1 are vulnerable to Incomplete Comparison with Missing…
CVE-2021-30246 — Critical (CVSS 9.1): In the jsrsasign package through 10.1.13 for Node.js, some invalid RSA PKCS#1 v1.5 signatures are mistakenly recognized…
CVE-2026-4601 — High (CVSS 8.7): Versions of the package jsrsasign before 11.1.1 are vulnerable to Missing Cryptographic Step via the…
CVE-2022-25898 — High (CVSS 7.7): The package jsrsasign before 10.5.25 are vulnerable to Improper Verification of Cryptographic Signature when JWS or JWT…

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Other CWE-369 (Divide By Zero) vulnerabilities

CVE-2021-32494 — Critical (CVSS 10.0): Radare2 has a division by zero vulnerability in Mach-O parser's rebase_buffer function. This allow attackers to create…
CVE-2017-11720 — Critical (CVSS 9.8): There is a division-by-zero vulnerability in LAME 3.99.5, caused by a malformed input file.
CVE-2020-20892 — High (CVSS 8.8): An issue was discovered in function filter_frame in libavfilter/vf_lenscorrection.c in Ffmpeg 4.2.1, allows attackers…
CVE-2025-4637 — High (CVSS 8.7): Divide By Zero vulnerability in davisking dlib allows remote attackers to cause a denial of service via a crafted…
CVE-2026-37232 — High (CVSS 8.6): An issue was discovered in OpenAirInterface5G 2.4.0 (nr-softmodem) in the E2SM-KPM RAN Function's PRB utilization…
CVE-2024-26945 — High (CVSS 8.4): In the Linux kernel, the following vulnerability has been resolved: crypto: iaa - Fix nr_cpus < nr_iaa case If…

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