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CVE-2026-31790

Incorrect Failure Handling in RSA KEM RSASVE Encapsulation

No exploitation reported by the sources we read.

  • Published2026-04-07
  • Fixed in3.6.2 · 3.5.6 · 3.4.5 · 3.3.7 · 3.0.20
  • WeaknessCWE-754

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-04-0722:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-31790?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-31790?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
OpenSSL
BranchAffectedFixed in
3.6≥ 3.6.0, < 3.6.23.6.2
3.5≥ 3.5.0, < 3.5.63.5.6
3.4≥ 3.4.0, < 3.4.53.4.5
3.3≥ 3.3.0, < 3.3.73.3.7
3.0≥ 3.0.0, < 3.0.203.0.20

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • edk2-toolsAlmaLinux:10all versions · fixed in 20251114-5.el10_2.2and 3 other packages
  • opensslAlmaLinux:10all versions · fixed in 1:3.5.5-2.el10_2.alma.1and 3 other packages
  • opensslAlmaLinux:9all versions · fixed in 1:3.5.5-2.el9_8and 3 other packages

Vendor advisories

  • CVE-2026-31790 Red Hat Product Security458 products fixed · 6 known affected

    openssl: openssl: Information Disclosure from Uninitialized Memory via Invalid RSA Public Key

    edk2-aarch64 as a component of Red Hat Enterprise Linux 9 · edk2-ovmf as a component of Red Hat Enterprise Linux 9 · edk2-tools as a component of Red Hat Enterprise Linux 9 · +3 more

  • RHSA-2026:84573 Red Hat Product Security40 products fixed

    Red Hat Security Advisory: openssl security update

  • RHSA-2026:84572 Red Hat Product Security30 products fixed

    Red Hat Security Advisory: openssl security update

  • RHSA-2026:83617 Red Hat Product Security39 products fixed

    Red Hat Security Advisory: openssl security update

  • RHSA-2026:82888 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.17.2

  • RHSA-2026:82857 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.18.2

33 more advisories

Full record on NVD

Fix

  1. Update OpenSSL to 3.6.2 · 3.5.6 · 3.4.5 · 3.3.7 · 3.0.20
  2. Vendor fix Red Hat Product Security RHSA-2026:84573 · 40 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258
  3. Vendor fix Red Hat Product Security RHSA-2026:82888 · 1 productBefore applying this update, make sure all previously released errata relevant to your system have been applied. The steps to apply the upgraded images are different depending on the installation plan approval policy you used when installing the cert-manager Operator for Red Hat OpenShift. - If t…
  4. Vendor fix Red Hat Product Security RHSA-2026:74674 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:74674
  5. Vendor fix Red Hat Product Security RHSA-2026:58981 · 3 productsPlease consult the RHUI Technology Preview Release Notes at https://access.redhat.com/articles/7141172 for instructions on how to use this image set.
  6. Vendor fix Red Hat Product Security RHSA-2026:54187 · 1 productFor OpenShift Container Platform 4.13 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  7. Vendor fix Red Hat Product Security RHSA-2026:43252 · 4 productsFor OpenShift Container Platform 4.14 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Published
2026-04-07
Last Modified
2026-07-24
NVD status
Modified
MSRC Title
Incorrect Failure Handling in RSA KEM RSASVE Encapsulation

Frequently asked questions

What is CVE-2026-31790?

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.

Is CVE-2026-31790 actively exploited?

Active exploitation of CVE-2026-31790 has not been confirmed. Its EPSS score was 1.0% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-31790?

CVE-2026-31790 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

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