HighPublic exploit

Private key recovery in jsrsasign DSA signing

IdentifiersCVE-2026-4601CWE-325· Missing Cryptographic Step

CVE-2026-4601 affects jsrsasign versions before 11.1.1. The flaw is in the DSA signing implementation, specifically the KJUR.crypto.DSA.signWithMessageHash process. The implementation fails to perform the required retry step when the generated DSA signature component r or s is zero. Instead of discarding the invalid result and regenerating the per-signature value, the library emits an invalid signature. Under conditions where an attacker can force r or s to be zero, the resulting signature leaks enough information for the attacker to solve for the DSA private key x. This is a cryptographic implementation flaw caused by omission of a required validation/retry step during signature generation.

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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 can lead to recovery of the DSA private signing key used by the vulnerable jsrsasign implementation. Once the private key is recovered, an attacker can forge DSA signatures, impersonate the legitimate signer, and compromise the confidentiality and integrity of systems or data that rely on that key for trust decisions. The available information indicates high confidentiality and integrity impact, with no direct availability impact.

Mitigation

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

If immediate upgrade is not possible, avoid using the vulnerable DSA signing path in jsrsasign, especially KJUR.crypto.DSA.signWithMessageHash, and disable or replace DSA-based signing operations where feasible. Prefer alternative, unaffected signature algorithms and prevent untrusted parties from influencing the signing process or inputs in ways that could trigger the invalid-signature condition. As a precaution, monitor for suspicious signature activity and plan key rotation for DSA keys that may have been exposed.

Remediation

Patch, then assume compromise.

Upgrade jsrsasign to version 11.1.1 or later, which contains the fix for the DSA signing flaw. The referenced fix is associated with commit 0710e392ec35de697ce11e4219c988ba2b5fe0eb and related pull request #645. Any DSA private keys used with vulnerable versions should be treated as potentially compromised if exposed to exploitable conditions; rotate and replace affected keys after upgrading.

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

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

Jsrsasign ProjectJsrsasignapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

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

8 SOURCESView more in app

cvefeed high severityNews

Mar 23, 2026

CVE-2026-4601 - Adobe jsrsasign Missing Cryptographic Step Vulnerability

A cryptographic flaw in jsrsasign before version 11.1.1 affecting DSA signing, where failure to retry when r or s is zero can allow private key recovery from an invalid signature.

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

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Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity7