RSA signature validation vulnerability on maleable encoded message in jsrsasign
### 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.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2021-30246US | critical9.1 | — | ||
In the jsrsasign package through 10.1.13 for Node.js, some invalid RSA PKCS#1 v1.5 signatures are mistakenly recognized to be valid. NOTE: there is no known practical attack. | ||||
references
External citations — patches, advisories, analysis.
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