⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● High · CVSS 7.4

How to Fix CVE-2026-4600: Authentication Bypass in jsrsasign

Other vulnerabilities in the same area that are worth patching alongside this one:

*By Sai Kiran Pandrala*

⚡ At a glance
SeverityCVSS 7.4 - High
Actively exploited?Not currently listed in CISA KEV
Affected0 < 11.1.1
Fixed inSee vendor advisory
Type (CWE)CWE-347: Improper Verification of Cryptographic Signature

What is CVE-2026-4600?

CVE-2026-4600 is an authentication bypass in jsrsasign. A flaw in the authentication or session-handling logic lets a remote attacker reach administrative functions without valid credentials. In several reported cases this leads directly to remote code execution. Vendor description: Versions of the package jsrsasign before 11.1.1 are vulnerable to Improper Verification of Cryptographic Signature via the DSA domain-parameter validation in KJUR.crypto.DSA.setPublic (and the related DSA/X509 verification flow in src/dsa-2.0.js). An attacker can forge DSA signatures or X.509 certificates that X509.verifySignature() accepts by supplying malicious domain parameters such as g=1, y=1, and a fixed r=1, which make the verification equation true for any hash.

Why this CVE matters

Authentication bypass on a network appliance or admin console is a top-tier target. Once the attacker is past the login, every administrative endpoint becomes available, including the ones that change settings, upload firmware, or run shell commands.

For deployments of jsrsasign that have been exposed to the public internet during the disclosure window, the operating assumption should be that scanning has already happened. Even where exploitation has not been publicly observed, scanning for the vulnerable fingerprint is cheap and routine. Patching closes the door; log review and credential rotation close out the rest of the response.

Am I affected?

You are affected if your installation matches any of these version ranges:

Check your installed version against the list above. If you cannot determine the version, treat the system as affected and follow the upgrade path below.

Open the product's About / version dialog or read the installed package metadata. Compare against the affected ranges in the vendor advisory.

How to fix CVE-2026-4600

  1. Read the vendor advisory in full: https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15370940
  2. Upgrade jsrsasign to the patched build listed in the vendor advisory.
  3. Back up the configuration (and database, where applicable) before upgrading.
  4. Rotate any credentials, API keys, or session tokens that the vulnerable service touched. An unauthenticated RCE-class flaw means anything the process could see should be treated as exposed.
  5. Apply the patch in a maintenance window. For HA pairs, upgrade the standby node first, fail over, then upgrade the former primary.
  6. Restart the affected service so the patched binary loads, then verify the new version (see verification section).

Upgrade jsrsasign


# CVE-2026-4600 affects jsrsasign 0 < 11.1.1.
# Fixed in 11.1.1. Vendor advisory: https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15370940

# 1. Identify the running version using the vendor-documented command.
#    (Open the product UI -> About, or run the CLI version probe.)

# 2. Stage the patched build named in the advisory.
#    Vendor advisory: https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15370940

# 3. Apply the upgrade. If the vendor ships a Linux package, pull it via your
#    distribution's package manager:
sudo apt update && sudo apt install --only-upgrade jsrsasign        # Debian / Ubuntu
sudo dnf upgrade jsrsasign                                          # RHEL / Rocky / Alma / Fedora

# 4. Restart the affected service so the new binary loads.
sudo systemctl restart jsrsasign 2>/dev/null || true

# 5. Re-run the version probe and confirm it matches 11.1.1.


# Windows-hosted installs of jsrsasign: apply via PSWindowsUpdate or the vendor MSI.
Install-Module PSWindowsUpdate -Force -SkipPublisherCheck -Confirm:$false
Get-WindowsUpdate -AcceptAll -Install -AutoReboot

Verify the fix landed


# CVE-2026-4600 verification checklist.

# 1. Confirm the running version matches 11.1.1 (replace the version probe with
#    the platform-specific command shown above).

# 2. Re-scan the host with your vulnerability scanner (Nessus, Qualys, Tenable,
#    OpenVAS, Wazuh). The scanner must no longer flag CVE-2026-4600.

# 3. Inspect recent service and kernel logs for crash-loops or rollback events.
journalctl -u <service-name> --since "10 minutes ago"
dmesg --since "10 minutes ago"

# 4. Cross-check the running build against the vendor advisory:
#    https://security.snyk.io/vuln/SNYK-JS-JSRSASIGN-15370940

If you cannot patch immediately

Restrict access to the affected administrative interface to trusted internal networks. Disable the vulnerable component if the vendor documents that as an interim option. Patch immediately when feasible.

How to verify the fix worked

If your installation was internet-reachable during the disclosure window, treat log review as part of the remediation rather than an optional follow-up. Look for unexpected administrator accounts in jsrsasign, scheduled tasks or cron jobs you did not create, new files in web-accessible directories, and outbound connections to addresses not in your baseline. Suspicious requests to the vulnerable endpoint immediately followed by successful 200-class responses with unusually large bodies are a strong indicator of exploitation.

Frequently asked questions

Is CVE-2026-4600 being exploited in the wild?

Public exploitation has not been confirmed by CISA at the time of writing. Treat the patch as time-sensitive anyway; reports often lag actual abuse.

Will a WAF or IDS rule fully mitigate CVE-2026-4600?

No. Network-layer filters can reduce noise and slow opportunistic scanners, but they will not stop a determined attacker. The vendor patch is the only durable fix.

Do I need to assume compromise if my jsrsasign was internet-facing and unpatched?

For an unauthenticated RCE-class flaw exposed to the public internet during the known exploitation window, yes. Review logs, rotate credentials the process could access, and look for unexpected accounts, scheduled tasks, or outbound connections.

References

*This guide was assembled from the official vendor advisory, the NVD record, and the CISA KEV catalog entry on 2026-05-25. Always confirm against the vendor advisory before applying changes in production.*