CVE-2026-85393Public exploitNetwork attack vector

Signature forgery via unchecked nested ASN.1 elements

Published Sep 3, 2026 · Updated Sep 3, 2026

Improper signature verification in Digital Bazaar Forge 1.4.0 and earlier allows remote attackers to forge RSA signatures for arbitrary messages. The RSA verification path accepts a nested DigestAlgorithm sequence with extra children because ASN.1 validation ignores unconsumed elements and only the outer DigestInfo count is checked. An attacker must supply a crafted signature to a consuming application that verifies it with a low-exponent RSA public key; acceptance can subvert integrity decisions based on the signed message.

CVSS severity8.7
High
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper signature verification in Digital Bazaar Forge 1.4.0 and earlier allows remote attackers to forge RSA signatures for arbitrary messages. The RSA verification path accepts a nested DigestAlgorithm sequence with extra children because ASN.1 validation ignores unconsumed elements and only the outer DigestInfo count is checked. An attacker must supply a crafted signature to a consuming application that verifies it with a low-exponent RSA public key; acceptance can subvert integrity decisions based on the signed message.

The record

CVE
CVE-2026-85393
Published
Sep 3, 2026
Updated
Sep 3, 2026
Vendor
Digital Bazaar
Product
Forge
Classifications
CWE-347
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=1.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Digital Bazaar · Forgeversion=0 <=1.4.0

Published CVSS scores

7.5VulnCheck CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
8.7VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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