HighPublic exploit

Improper DSA Signature Verification in jsrsasign

IdentifiersCVE-2026-4600CWE-347· Improper Verification of…

CVE-2026-4600 affects jsrsasign versions before 11.1.1. The vulnerability is an improper verification of cryptographic signatures in the DSA public-key/domain-parameter handling implemented in KJUR.crypto.DSA.setPublic and the related DSA/X.509 verification flow in src/dsa-2.0.js. The library fails to properly validate attacker-supplied DSA domain parameters during signature verification. As described in the provided content, an attacker can supply malicious parameters such as g=1 and y=1 together with a fixed r=1 so that the DSA verification equation evaluates as valid for any hash value. As a result, forged DSA signatures and forged X.509 certificates can be accepted by X509.verifySignature() as authentic.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an attacker to bypass signature verification guarantees for affected DSA and X.509 verification paths. This can enable acceptance of forged DSA signatures and forged X.509 certificates as valid, undermining trust decisions that depend on jsrsasign verification results. The primary impact is on integrity and authenticity, and depending on application usage, may also expose confidential data or protected functionality by allowing attackers to impersonate trusted signers or present untrusted certificates that are incorrectly treated as trusted. No direct availability impact is indicated in the provided content.

Mitigation

If you can’t patch tonight, do this now.

Until patching is completed, avoid relying on affected jsrsasign versions for DSA-based signature or X.509 certificate verification, especially where untrusted certificates, keys, or signature inputs can be supplied by external parties. Prefer alternative verification implementations that correctly validate DSA domain parameters, and restrict or disable DSA-based trust paths where feasible. Treat any verification result from affected versions as potentially unreliable if the attacker can influence the certificate, public key, or DSA parameters being verified.

Remediation

Patch, then assume compromise.

Upgrade jsrsasign to version 11.1.1 or later, which contains the fix for the DSA domain-parameter validation issue. Review any application components that rely on KJUR.crypto.DSA.setPublic, DSA signature verification, or X509.verifySignature() to ensure they are using the patched library version. If forged signatures or certificates may have been accepted in production, revalidate trust decisions and certificate/signature artifacts using a fixed implementation.

PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

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VendorProductType

Jsrsasign ProjectJsrsasignapplication

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ACTIVITY FEED

Recent activity

4 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

4 SOURCESView more in app

cvefeed high severityNews

Mar 23, 2026

CVE-2026-4600 - Apache Commons Crypto DSA Signature Forgery

An improper cryptographic signature verification vulnerability in jsrsasign before 11.1.1 that allows forged DSA signatures or X.509 certificates to be accepted due to insufficient DSA domain-parameter validation.

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Exposure mapping

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Threat actor evidence

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Associated malware

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Detection signatures

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Vendor-by-vendor mapping

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Social activity3