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.
Published: 2026-04-07
Score: 5.9 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

No analysis available yet.

Remediation

No remediation available yet.

Tracking

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Advisories
Source ID Title
Debian DSA Debian DSA DSA-6201-1 openssl security update
History

Wed, 08 Apr 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-824
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N'}

threat_severity

Moderate


Tue, 07 Apr 2026 22:15:00 +0000

Type Values Removed Values Added
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.
Title Incorrect Failure Handling in RSA KEM RSASVE Encapsulation
Weaknesses CWE-754
References

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: openssl

Published:

Updated: 2026-04-07T22:00:56.698Z

Reserved: 2026-03-09T15:56:53.191Z

Link: CVE-2026-31790

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-04-07T22:16:21.770

Modified: 2026-04-07T22:16:21.770

Link: CVE-2026-31790

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-04-07T00:00:00Z

Links: CVE-2026-31790 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses