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Message-ID: <2de6e09f877b50b3fd0e5f3141a49473b80e3f29.camel@openssl.foundation>
Date: Tue, 07 Apr 2026 18:28:42 +0200
From: Tomas Mraz <tomas@...nssl.foundation>
To: oss-security@...ts.openwall.com
Subject: OpenSSL Security Advisory
OpenSSL Security Advisory [7th April 2026]
==========================================
Incorrect Failure Handling in RSA KEM RSASVE Encapsulation (CVE-2026-31790)
===========================================================================
Severity: Moderate
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.
OpenSSL 1.0.2 and 1.1.1 are not affected by this issue.
OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0 are vulnerable to this issue.
OpenSSL 3.0 users should upgrade to OpenSSL 3.0.20.
OpenSSL 3.3 users should upgrade to OpenSSL 3.3.7.
OpenSSL 3.4 users should upgrade to OpenSSL 3.4.5.
OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6.
OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2.
This issue was reported by Simo Sorce (Red Hat) on 23rd Feburary 2026.
The fix was developed by Nikola Pajkovsky.
Out-of-bounds Read in AES-CFB-128 on X86-64 with AVX-512 Support (CVE-2026-28386)
=================================================================================
Severity: Low
Issue summary: Applications using AES-CFB128 encryption or decryption on
systems with AVX-512 and VAES support can trigger an out-of-bounds read
of up to 15 bytes when processing partial cipher blocks.
Impact summary: This out-of-bounds read may trigger a crash which leads to
Denial of Service for an application if the input buffer ends at a memory
page boundary and the following page is unmapped. There is no information
disclosure as the over-read bytes are not written to output.
The vulnerable code path is only reached when processing partial blocks
(when a previous call left an incomplete block and the current call provides
fewer bytes than needed to complete it). Additionally, the input buffer
must be positioned at a page boundary with the following page unmapped.
CFB mode is not used in TLS/DTLS protocols, which use CBC, GCM, CCM, or
ChaCha20-Poly1305 instead. For these reasons the issue was assessed as
Low severity according to our Security Policy.
Only x86-64 systems with AVX-512 and VAES instruction support are affected.
Other architectures and systems without VAES support use different code
paths that are not affected.
OpenSSL FIPS module in 3.6 version is affected by this issue.
OpenSSL 3.0, 3.3, 3.4, 3.5, 1.1.1 and 1.0.2 are not vulnerable to this issue.
OpenSSL 3.6 is vulnerable to this issue.
OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2.
This issue was reported on 6th January 2026 by Stanislav Fort and Pavel Kohout
(Aisle Research).
The fix was developed by Stanislav Fort and Pavel Kohout (Aisle Research).
It was independently reported on 10th March 2026 by Alex Gaynor (Anthropic).
Potential Use-after-free in DANE Client Code (CVE-2026-28387)
=============================================================
Severity: Low
Issue summary: An uncommon configuration of clients performing DANE TLSA-based
server authentication, when paired with uncommon server DANE TLSA records, may
result in a use-after-free and/or double-free on the client side.
Impact summary: A use after free can have a range of potential consequences
such as the corruption of valid data, crashes or execution of arbitrary code.
However, the issue only affects clients that make use of TLSA records with both
the PKIX-TA(0/PKIX-EE(1) certificate usages and the DANE-TA(2) certificate
usage.
By far the most common deployment of DANE is in SMTP MTAs for which RFC7672
recommends that clients treat as "unusable" any TLSA records that have the PKIX
certificate usages. These SMTP (or other similar) clients are not vulnerable
to this issue. Conversely, any clients that support only the PKIX usages, and
ignore the DANE-TA(2) usage are also not vulnerable.
The client would also need to be communicating with a server that publishes a
TLSA RRset with both types of TLSA records.
No FIPS modules are affected by this issue, the problem code is outside the
FIPS module boundary.
OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0 and 1.1.1 are vulnerable to this issue.
OpenSSL 1.0.2 is not affected by this issue.
OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2.
OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6.
OpenSSL 3.4 users should upgrade to OpenSSL 3.4.5.
OpenSSL 3.3 users should upgrade to OpenSSL 3.3.7.
OpenSSL 3.0 users should upgrade to OpenSSL 3.0.20.
OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1zg (premium
support customers only).
This issue was reported on the 8th of January 2026 by Igor Morgenstern (Aisle
Research). The fix was developed by Viktor Dukhovni and Alexandr Nedvedicky.
NULL Pointer Dereference When Processing a Delta CRL (CVE-2026-28388)
=====================================================================
Severity: Low
Issue summary: When a delta CRL that contains a Delta CRL Indicator extension
is processed a NULL pointer dereference might happen if the required CRL
Number extension is missing.
Impact summary: A NULL pointer dereference can trigger a crash which
leads to a Denial of Service for an application.
When CRL processing and delta CRL processing is enabled during X.509
certificate verification, the delta CRL processing does not check
whether the CRL Number extension is NULL before dereferencing it.
When a malformed delta CRL file is being processed, this parameter
can be NULL, causing a NULL pointer dereference.
Exploiting this issue requires the X509_V_FLAG_USE_DELTAS flag to be enabled in
the verification context, the certificate being verified to contain a
freshestCRL extension or the base CRL to have the EXFLAG_FRESHEST flag set, and
an attacker to provide a malformed CRL to an application that processes it.
The vulnerability is limited to Denial of Service and cannot be escalated to
achieve code execution or memory disclosure. For that reason the issue was
assessed as Low severity according to our Security Policy.
The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue,
as the affected code is outside the OpenSSL FIPS module boundary.
OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0, 1.1.1 and 1.0.2 are vulnerable to this issue.
OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2.
OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6.
OpenSSL 3.4 users should upgrade to OpenSSL 3.4.5.
OpenSSL 3.3 users should upgrade to OpenSSL 3.3.7.
OpenSSL 3.0 users should upgrade to OpenSSL 3.0.20.
OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1zg
(premium support customers only).
OpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zp
(premium support customers only).
This issue was reported on 8th January 2026 by Igor Morgenstern (Aisle
Research). The fix was developed by Igor Morgenstern (Aisle Research).
Possible NULL Dereference When Processing CMS KeyAgreeRecipientInfo (CVE-2026-28389)
====================================================================================
Severity: Low
Issue summary: During processing of a crafted CMS EnvelopedData message
with KeyAgreeRecipientInfo a NULL pointer dereference can happen.
Impact summary: Applications that process attacker-controlled CMS data may
crash before authentication or cryptographic operations occur resulting in
Denial of Service.
When a CMS EnvelopedData message that uses KeyAgreeRecipientInfo is
processed, the optional parameters field of KeyEncryptionAlgorithmIdentifier
is examined without checking for its presence. This results in a NULL
pointer dereference if the field is missing.
Applications and services that call CMS_decrypt() on untrusted input
(e.g., S/MIME processing or CMS-based protocols) are vulnerable.
The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this
issue, as the affected code is outside the OpenSSL FIPS module boundary.
OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0, 1.1.1 and 1.0.2 are vulnerable to this issue.
OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2.
OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6.
OpenSSL 3.4 users should upgrade to OpenSSL 3.4.5.
OpenSSL 3.3 users should upgrade to OpenSSL 3.3.7.
OpenSSL 3.0 users should upgrade to OpenSSL 3.0.20.
OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1zg.
(premium support customers only).
OpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zp.
(premium support customers only).
This issue was reported on 13th February 2026 by Nathan Sportsman
(Praetorian), on 25th February 2026 by Daniel Rhea, on 15th March 2026
by Jaeho Nam (Seoul National University), on 26th March 2026 by
Muhammad Daffa, on 27th March 2026 by Zhanpeng Liu (Tencent Xuanwu Lab),
Guannan Wang (Tencent Xuanwu Lab) and Guancheng Li (Tencent Xuanwu Lab)
and on 30th March 2026 by Joshua Rogers.
The fix was developed by Neil Horman.
Possible NULL Dereference When Processing CMS KeyTransportRecipientInfo (CVE-2026-28390)
========================================================================================
Severity: Low
Issue summary: During processing of a crafted CMS EnvelopedData message
with KeyTransportRecipientInfo a NULL pointer dereference can happen.
Impact summary: Applications that process attacker-controlled CMS data may
crash before authentication or cryptographic operations occur resulting in
Denial of Service.
When a CMS EnvelopedData message that uses KeyTransportRecipientInfo with
RSA-OAEP encryption is processed, the optional parameters field of
RSA-OAEP SourceFunc algorithm identifier is examined without checking
for its presence. This results in a NULL pointer dereference if the field
is missing.
Applications and services that call CMS_decrypt() on untrusted input
(e.g., S/MIME processing or CMS-based protocols) are vulnerable.
The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this
issue, as the affected code is outside the OpenSSL FIPS module boundary.
OpenSSL 3.6, 3.5, 3.4, 3.3, 3.0, 1.1.1 and 1.0.2 are vulnerable to this issue.
OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2.
OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6.
OpenSSL 3.4 users should upgrade to OpenSSL 3.4.5.
OpenSSL 3.3 users should upgrade to OpenSSL 3.3.7.
OpenSSL 3.0 users should upgrade to OpenSSL 3.0.20.
OpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1zg.
(premium support customers only).
OpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zp.
(premium support customers only).
This issue was reported on 26th March 2026 by Muhammad Daffa, on 27th March
2026 by Zhanpeng Liu (Tencent Xuanwu Lab), Guannan Wang (Tencent Xuanwu Lab)
and Guancheng Li (Tencent Xuanwu Lab), on 30th March 2026 by Joshua
Rogers and on 31st March 2026 by Chanho Kim. The fix was developed by
Neil Horman.
Heap Buffer Overflow in Hexadecimal Conversion (CVE-2026-31789)
===============================================================
Severity: Low
Issue summary: Converting an excessively large OCTET STRING value to
a hexadecimal string leads to a heap buffer overflow on 32 bit platforms.
Impact summary: A heap buffer overflow may lead to a crash or possibly
an attacker controlled code execution or other undefined behavior.
If an attacker can supply a crafted X.509 certificate with an excessively
large OCTET STRING value in extensions such as the Subject Key Identifier
(SKID) or Authority Key Identifier (AKID) which are being converted to hex,
the size of the buffer needed for the result is calculated as multiplication
of the input length by 3. On 32 bit platforms, this multiplication may overflow
resulting in the allocation of a smaller buffer and a heap buffer overflow.
Applications and services that print or log contents of untrusted X.509
certificates are vulnerable to this issue. As the certificates would have
to have sizes of over 1 Gigabyte, printing or logging such certificates
is a fairly unlikely operation and only 32 bit platforms are affected,
this issue was assigned Low severity.
The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this
issue, as the affected code is outside the OpenSSL FIPS module boundary.
OpenSSL 3.6, 3.5, 3.4, 3.3 and 3.0 are vulnerable to this issue.
OpenSSL 1.1.1 and 1.0.2 are not affected by this issue.
OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2.
OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6.
OpenSSL 3.4 users should upgrade to OpenSSL 3.4.5.
OpenSSL 3.3 users should upgrade to OpenSSL 3.3.7.
OpenSSL 3.0 users should upgrade to OpenSSL 3.0.20.
This issue was reported on 16th February 2026 by Quoc Tran (Xint.io - US Team).
The fix was developed by Igor Ustinov.
General Advisory Notes
======================
URL for this Security Advisory:
https://openssl-library.org/news/secadv/20260407.txt
Note: the online version of the advisory may be updated with additional details
over time.
Only currently supported releases have been analysed. OpenSSL 3.1 and 3.2 are
out of support and have not been analysed.
For details of OpenSSL severity classifications please see:
https://openssl-library.org/policies/general/security-policy/
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