https://vulnerability.circl.lu Contains only the most 10 recent entries. http://www.rssboard.org/rss-specification python-feedgen en Tue, 29 Sep 2026 14:44:46 +0000 https://vulnerability.circl.lu/vuln/cve-2026-42768 <p><strong>Affected:</strong> OpenSSL</p> <p>Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output.</p> <p>Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim&#39;s vulnerable application as a way to decrypt or sign messages with the victim&#39;s private RSA key.</p> <p>The attack is possible in 2 variants.</p> <p>1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success.</p> <p>An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim&#39;s public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available.</p> <p>That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO &#39;98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim&#39;s key or forges any PKCS#1 v1.5 signature under it.</p> <p>2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted.</p> <p>An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle.</p> <p>We…</p> <p><strong>Affected:</strong> OpenSSL</p> <p>Issue summary: The CMS_decrypt and PKCS7_decrypt functions are vulnerable to Bleichenbacher-style attack when an attacker is able to provide the CMS or S/MIME messages and observe the error code and/or decryption output.</p> <p>Impact summary: The Bleichenbacher-style attack allows an attacker to use the victim&#39;s vulnerable application as a way to decrypt or sign messages with the victim&#39;s private RSA key.</p> <p>The attack is possible in 2 variants.</p> <p>1. The decryption API (CMS_decrypt(), PKCS7_decrypt()) is used without providing the recipient certificate. In this case OpenSSL iterates over every KeyTransRecipientInfo (KTRI) without stopping at the first success.</p> <p>An attacker who authors a message with two KTRI entries — the first one wrapping a real CEK under the victim&#39;s public key, the second with an arbitrary probe ciphertext — obtains opportunity to iterate the 2nd KTRI to get a valid PKCS#1 v1.5 padding if the error code of the application is available.</p> <p>That is a Bleichenbacher oracle (Bleichenbacher, CRYPTO &#39;98): an adaptive-chosen-ciphertext side channel from which the attacker decrypts any RSA ciphertext to the victim&#39;s key or forges any PKCS#1 v1.5 signature under it.</p> <p>2. When the decryption API (CMS_decrypt(), PKCS7_decrypt()) is provided with the recipient certificate, and the recipient is not found, a random key is substituted.</p> <p>An attacker who authors a message and is able to compare both error code and the result of the decryption, can mount a Bleichenbacher oracle.</p> <p>We…</p> https://vulnerability.circl.lu/vuln/cve-2026-42768