CVE-2026-31790 Incorrect Failure Handling in RSA KEM RSASVE Encapsulation

High 7.5 Published 7 Apr 2026 Updated 12 May 2026

Attackers can read uninitialized memory contents via RSA KEM encapsulation if invalid public keys are used without validation, leaking sensitive data.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-31790?

CVE-2026-31790 is a high-severity vulnerability in Openssl Openssl, published on 7 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Weakness: CWE-754

Which versions are affected by CVE-2026-31790?

It affects 1 product.

Linux distribution packages (40)

`openssl` AlmaLinux:9	All versions	`1:3.5.5-2.el9_8`
`openssl-devel` AlmaLinux:9	All versions	`1:3.5.5-2.el9_8`
`openssl-libs` AlmaLinux:9	All versions	`1:3.5.5-2.el9_8`
`openssl-perl` AlmaLinux:9	All versions	`1:3.5.5-2.el9_8`
`openssl-fips-provider` Red Hat:enterprise_linux:10.2	All versions	`0:3.0.7-11.el10_2`
`openssl-fips-provider-so` Red Hat:enterprise_linux:10.2	All versions	`0:3.0.7-11.el10_2`
`openssl-fips-provider-so-debuginfo` Red Hat:enterprise_linux:10.2	All versions	`0:3.0.7-11.el10_2`
`openssl-fips-provider-so-debugsource` Red Hat:enterprise_linux:10.2	All versions	`0:3.0.7-11.el10_2`
`openssl-debuginfo` Red Hat:enterprise_linux:9::appstream	All versions	`1:3.5.5-2.el9_8`
`openssl-debugsource` Red Hat:enterprise_linux:9::appstream	All versions	`1:3.5.5-2.el9_8`
`openssl-devel` Red Hat:enterprise_linux:9::appstream	All versions	`1:3.5.5-2.el9_8`
`openssl-libs-debuginfo` Red Hat:enterprise_linux:9::appstream	All versions	`1:3.5.5-2.el9_8`
`openssl-perl` Red Hat:enterprise_linux:9::appstream	All versions	`1:3.5.5-2.el9_8`
`openssl` Red Hat:enterprise_linux:9::baseos	All versions	`1:3.5.5-2.el9_8`
`openssl-debuginfo` Red Hat:enterprise_linux:9::baseos	All versions	`1:3.5.5-2.el9_8`
`openssl-debugsource` Red Hat:enterprise_linux:9::baseos	All versions	`1:3.5.5-2.el9_8`
`openssl-fips-provider` Red Hat:enterprise_linux:9::baseos	All versions	`0:3.0.7-11.el9_8`
`openssl-fips-provider-so` Red Hat:enterprise_linux:9::baseos	All versions	`0:3.0.7-11.el9_8`
`openssl-fips-provider-so-debuginfo` Red Hat:enterprise_linux:9::baseos	All versions	`0:3.0.7-11.el9_8`
`openssl-fips-provider-so-debugsource` Red Hat:enterprise_linux:9::baseos	All versions	`0:3.0.7-11.el9_8`
`openssl-libs` Red Hat:enterprise_linux:9::baseos	All versions	`1:3.5.5-2.el9_8`
`openssl-libs-debuginfo` Red Hat:enterprise_linux:9::baseos	All versions	`1:3.5.5-2.el9_8`
`openssl-fips-provider` Red Hat:enterprise_linux_eus:10.0	All versions	`0:3.0.7-11.el10_0`
`openssl-fips-provider-so` Red Hat:enterprise_linux_eus:10.0	All versions	`0:3.0.7-11.el10_0`
`openssl-fips-provider-so-debuginfo` Red Hat:enterprise_linux_eus:10.0	All versions	`0:3.0.7-11.el10_0`
`openssl-fips-provider-so-debugsource` Red Hat:enterprise_linux_eus:10.0	All versions	`0:3.0.7-11.el10_0`
`openssl-fips-provider` Red Hat:hummingbird:1	All versions	`0:3.0.7-1.2.hum1`
`openssl-fips-provider-so` Red Hat:hummingbird:1	All versions	`0:3.0.7-1.2.hum1`
`openssl-fips-provider` Red Hat:rhel_e4s:9.2::baseos	All versions	`0:3.0.7-11.el9_0`
`openssl-fips-provider-debugsource` Red Hat:rhel_e4s:9.2::baseos	All versions	`0:3.0.7-11.el9_0`
`openssl-fips-provider-so` Red Hat:rhel_e4s:9.2::baseos	All versions	`0:3.0.7-11.el9_0`
`openssl-fips-provider-so-debuginfo` Red Hat:rhel_e4s:9.2::baseos	All versions	`0:3.0.7-11.el9_0`
`openssl-fips-provider` Red Hat:rhel_e4s:9.4::baseos	All versions	`0:3.0.7-11.el9_0`
`openssl-fips-provider-debugsource` Red Hat:rhel_e4s:9.4::baseos	All versions	`0:3.0.7-11.el9_0`
`openssl-fips-provider-so` Red Hat:rhel_e4s:9.4::baseos	All versions	`0:3.0.7-11.el9_0`
`openssl-fips-provider-so-debuginfo` Red Hat:rhel_e4s:9.4::baseos	All versions	`0:3.0.7-11.el9_0`
`openssl-fips-provider` Red Hat:rhel_eus:9.6::baseos	All versions	`0:3.0.7-11.el9_0`
`openssl-fips-provider-debugsource` Red Hat:rhel_eus:9.6::baseos	All versions	`0:3.0.7-11.el9_0`
`openssl-fips-provider-so` Red Hat:rhel_eus:9.6::baseos	All versions	`0:3.0.7-11.el9_0`
`openssl-fips-provider-so-debuginfo` Red Hat:rhel_eus:9.6::baseos	All versions	`0:3.0.7-11.el9_0`

Products include Openssl Openssl.

How do I fix CVE-2026-31790?

Apply the vendor's patch.

Is CVE-2026-31790 being exploited?

There is no known exploitation of CVE-2026-31790 in the wild and no public exploit code.

All Openssl Openssl vulnerabilities

Sources

Also known as ALPINE-CVE-2026-31790, ALSA-2026:19218, AZL-81950, BELL-CVE-2026-31790, CLSA-2026-1777948139, CLSA-2026-1778072039 and 19 more.