PT-2021-18683 · Jsrsasign · Jsrsasign

Yahyazadeh · Published 2021-04-07 · Updated 2022-02-09 · CVE-2021-30246

Positive Technologies (AI Summary)

CVSS v3.1

9.1

Critical

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Name of the Vulnerable Software and Affected Versions jsrsasign versions through 10.1.13

Description The issue concerns the validation of RSA PKCS#1 v1.5 signatures. Specifically, some invalid signatures are mistakenly recognized as valid due to insufficient checking of the decoded RSA signature value. This value consists of a specific form: 01(ff...(8 or more ffs)...ff)00[ASN.1 OF DigestInfo], and its byte length must match the RSA key length. However, crafting a message for a practical attack is considered very hard. There is no known practical attack.

Recommendations For versions through 10.1.13, upgrade to 10.2.0 or later to resolve the issue. As a temporary workaround, consider avoiding the use of RSA signature validation in jsrsasign until a patch is applied.

Fix

Improper Verification of Cryptographic Signature

Weakness Enumeration

CWE-347

Related Identifiers

CVE-2021-30246

GHSA-27FJ-MC8W-J9WG

GHSA-H87Q-G2WP-47PJ

Affected Products

Jsrsasign

References · 9

• https://nvd.nist.gov/vuln/detail/CVE-2021-30246 · Security Note
• https://osv.dev/vulnerability/CVE-2021-30246 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-27fj-mc8w-j9wg · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-h87q-g2wp-47pj · Vendor Advisory
• https://github.com/kjur/jsrsasign/issues/478 · Note
• https://github.com/kjur/jsrsasign/releases/tag/10.1.13 · Note
• https://github.com/kjur/jsrsasign/security/advisories/GHSA-27fj-mc8w-j9wg · Note
• https://github.com/kjur/jsrsasign/releases/tag/10.2.0 · Note
• https://kjur.github.io/jsrsasign · Note