CVE-2026-31790

01/Description

Issue summary: Applications using RSASVE key encapsulation to establish a secret encryption key can send contents of an uninitialized memory buffer to a malicious peer. Impact summary: The uninitialized buffer might contain sensitive data from the previous execution of the application process which leads to sensitive data leakage to an attacker. RSA_public_encrypt() returns the number of bytes written on success and -1 on error. The affected code tests only whether the return value is non-zero. As a result, if RSA encryption fails, encapsulation can still return success to the caller, set the output lengths, and leave the caller to use the contents of the ciphertext buffer as if a valid KEM ciphertext had been produced. If applications use EVP_PKEY_encapsulate() with RSA/RSASVE on an attacker-supplied invalid RSA public key without first validating that key, then this may cause stale or uninitialized contents of the caller-provided ciphertext buffer to be disclosed to the attacker in place of the KEM ciphertext. As a workaround calling EVP_PKEY_public_check() or EVP_PKEY_public_check_quick() before EVP_PKEY_encapsulate() will mitigate the issue. The FIPS modules in 3.6, 3.5, 3.4, 3.3, 3.1 and 3.0 are affected by this issue.

02/Affected products

openssl: openssl

03/References7

• openssl-library.org/news/secadv/20260407.txt Vendor Advisory
• github.com/openssl/openssl/commit/001e01db3e996e13ffc72386fe79d… Patch
• github.com/openssl/openssl/commit/abd8b2eec7e3f3fda60ecfb68498b… Patch
• github.com/openssl/openssl/commit/b922e24e5b23ffb9cb9e14cadff23… Patch
• github.com/openssl/openssl/commit/d5f8e71cd0a54e961d0c3b174348f… Patch
• github.com/openssl/openssl/commit/eed200f58cd8645ed77e46b7e9f76… Patch
• cert-portal.siemens.com/productcert/html/ssa-032379.html