CVE-2021-30246
RSA signature validation vulnerability on maleable encoded message in jsrsasign
Description
### Impact Vulnerable jsrsasign will accept RSA signature with improper PKCS#1.5 padding. Decoded RSA signature value consists following form: `01(ff...(8 or more ffs)...ff)00[ASN.1 OF DigestInfo]` Its byte length must be the same as RSA key length, however such checking was not sufficient. To make crafted message for practical attack is very hard. ### Patches Users validating RSA signature should upgrade to 10.2.0 or later. ### Workarounds There is no workaround. Not to use RSA signature validation in jsrsasign. ### ACKNOWLEDGEMENT Thanks to Daniel Yahyazadeh @yahyazadeh for reporting and analyzing this vulnerability.
How to fix CVE-2021-30246
To remediate CVE-2021-30246, upgrade the affected package to a fixed version below.
- —upgrade to 10.2.0 or later
Is CVE-2021-30246 being exploited?
Low — EPSS is 0.2%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 10.2.0
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | CRITICAL9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |