CVE-2026-77696

Timing Side-Channel in SM2 Signature Generation

Issue summary: SM2 signature generation uses non-constant-time arithmetic on secret values, forming a timing side-channel. Impact summary: An attacker able to measure SM2 signing times may learn information about the per-signature secret nonce, which over many signatures can, via a lattice / Hidden Number Problem attack, lead to recovery of the private key. CWE: CWE-208: Observable Timing Discrepancy Description: SM2 signature generation computes the signature value using variable-time BIGNUM operations on the secret nonce and the private key, so the time taken to produce an SM2 signature depends on these secret values, forming a timing side-channel. Applications performing SM2 signature generation are affected on all platforms. FIPS Impact: no SM2 is not a FIPS algorithm.

CVSS 3.1 · 3.7 Low EPSS < 1% KEV · Not listed

Vendors

Openssl

Products

Openssl

CVE-2026-77214

libexpat Heap Buffer Over-read in xmlparse.c via XML_ParseBuffer

libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c. XML_ParseBuffer advances the parse buffer end with parser->m_bufferEnd += len using a caller-supplied length that is not validated against the allocated buffer size, so repeated XML_ParseBuffer calls move m_bufferEnd past the end of the heap allocation and subsequent parsing reads out of bounds. Reaching this path requires a parse buffer to already be present; otherwise XML_ParseBuffer returns XML_ERROR_NO_BUFFER. A buffer is present after a prior call to XML_GetBuffer, either directly (the common case) or indirectly through a prior XML_Parse call that allocates the buffer internally. The over-read discloses adjacent heap memory to the calling application, recovering heap pointers, libc function pointers, and code pointers sufficient to defeat ASLR and build further exploitation primitives.

CVSS 4.0 · 8.3 High EPSS < 1% KEV · Not listed

Vendors

Libexpat Libexpat Project

Products

Expat Libexpat

CVE-2026-76957

libexpat: libexpat: Memory corruption vulnerability allows arbitrary code execution or denial of service

libexpat before 2.8.4 lacks handler call depth tracking with custom encoding callbacks. Thus, a use-after-free can occur. NOTE: this is similar to CVE-2026-50219, CVE-2026-56131 and CVE-2026-56412.

CVSS 3.1 · 4.9 Medium EPSS < 1% KEV · Not listed

Vendors

Libexpat Project

Products

Libexpat

CVE-2026-75806

Unauthenticated and Undersized DTLS 1.2 AEAD Record Causes DoS

Issue summary: An established DTLS 1.2 association using an AEAD cipher suite can be terminated by a single unauthenticated datagram whose encrypted fragment is shorter than the mandatory explicit IV and authentication tag overhead. Impact summary: An attacker who can send a datagram that is routed to an existing DTLS 1.2 association can tear that association down without knowing any key material. This is a Denial of Service limited to the targeted association. There is no memory safety or confidentiality impact. CWE: CWE-1284: Improper Validation of Specified Quantity in Input Description: In TLS 1.2 and DTLS 1.2 every record protected by an AEAD cipher suite carries an explicit IV followed by the ciphertext and an authentication tag. When decrypting such a record the record layer passed the record length to the cipher implementation before checking that the record was long enough to contain the explicit IV and the tag. For a record shorter than that overhead the cipher implementation rejected the impossible length, and the record layer treated this as an internal failure and raised a fatal internal_error alert instead of treating the record as one that failed authentication. In TLS 1.2 the same record causes a fatal internal_error alert instead of the expected bad_record_mac alert. Since any undecryptable record already terminates a TLS connection, this is a protocol conformance issue rather than a security issue in TLS. The fix validates the record length against the explicit IV and tag length before any AEAD processing, so that TLS reports bad_record_mac and DTLS silently discards the record. FIPS impact: no The affected code is outside the FIPS module boundary.

CVSS 3.1 · 5.3 Medium EPSS 1.2% KEV · Not listed

Vendors

Openssl

Products

Openssl

CVE-2026-75805

NULL Pointer Dereference in CMP Client Revocation Response Handling

Issue summary: A CMP client that requests certificate revocation on the basis of a PKCS#10 CSR may dereference a NULL pointer and terminate abnormally when processing a crafted revocation response. Impact summary: The NULL pointer dereference happens on a read which leads to a crash and a Denial of Service for the affected client application. CWE: CWE-476: NULL-pointer dereference Description: A CMP client revoking a certificate has to tell the server which certificate to revoke, and may do so by supplying a PKCS#10 CSR instead of the certificate itself or its issuer name and serial number. This is 'openssl cmp -cmd rr -csr <file>' on the command line, or OSSL_CMP_exec_RR_ses() with the certificate supplied via OSSL_CMP_CTX_set1_p10CSR() through the API. A CSR does not contain the issuer name and serial number of the certificate, so the client does not send them. A server may optionally name the certificate it revoked in its response, and the client then compares that name against what it sent. Having sent neither an issuer name nor a serial number, it has nothing to compare against, and a server returning a specially crafted name causes the client to read from a NULL pointer and crash. The revocation response is checked for valid message protection before the affected code is reached, so an attacker must be a malicious or compromised CMP server, or a man-in-the-middle in possession of the secret used for message protection. Clients that identify the certificate to be revoked by a certificate or by issuer and serial number rather than by a PKCS#10 CSR are not affected. FIPS impact: no No FIPS modules are affected by this issue, as the CMP protocol implementation is outside the OpenSSL FIPS module boundary.

CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed

Vendors

Openssl

Products

Openssl

CVE-2026-72522

expat: libexpat: Denial of Service due to incorrect Unicode surrogate handling

libexpat before 2.8.3 has an out-of-bounds read and resultant infinite loop because low surrogates are treated the same as high surrogates during Unicode processing in the *_toUtf16 functions.

CVSS 3.1 · 6.2 Medium EPSS < 1% KEV · Not listed

Vendors

Libexpat Project

Products

Libexpat

CVE-2026-6019

BaseCookie.js_output() does not neutralize embedded characters

http.cookies.Morsel.js_output() returns an inline <script> snippet and only escapes " for JavaScript string context. It does not neutralize the HTML parser-sensitive sequence </script> inside the generated script element. Mitigation base64-encodes the cookie value to disallow escaping using cookie value.

CVSS 4.0 · 2.1 Low EPSS < 1% KEV · Not listed

Vendors

Python

Products

Cpython Python

CVE-2026-66046

Expat Denial of Service via storeAtts() Quadratic Complexity

Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring authentication, external entity resolution, or non-default parser options.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Libexpat Project

Products

Libexpat

CVE-2026-66034

libssh2 Heap Out-of-Bounds Read via publickey subsystem

libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an uninitialized pointer via the publickey subsystem. In libssh2_publickey_list_fetch(), the version 1 response parser reads a server-controlled comment_len value and advances the parse pointer without verifying sufficient bytes remain in the buffer, causing the out-of-bounds read to leak heap pointers from adjacent allocations defeating ASLR, followed by heap allocator state corruption when the error cleanup path frees an uninitialized pointer from a non-zeroed realloc() region.

CVSS 4.0 · 7.7 High EPSS < 1% KEV · Not listed

Vendors

Libssh2 Redhat

Products

Libssh2 Hummingbird

CVE-2026-66032

libssh2 Double-Free Heap Corruption via sftp_open()

libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open() function in src/sftp.c that allows a malicious SSH server to corrupt the heap of any authenticated client opening an SFTP session. When a server responds to SSH_FXP_OPEN with SSH_FXP_STATUS containing FX_OK, the response data buffer is freed, and if a subsequent sftp_packet_require() call returns a specific error such as LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, the same pointer is freed a second time, enabling tcache dup conditions on glibc systems that allow overlapping allocations and function pointer overwrites.

CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed

Vendors

Libssh2 Redhat

Products

Libssh2 Hummingbird

CVE-2026-58051

libssh2 - Free of Uninitialized Pointer in publickey List Cleanup

libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup path leaves libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-influenceable attrs pointer in a connecting libssh2 client.

CVSS 4.0 · 8.3 High EPSS < 1% KEV · Not listed

Vendors

Libssh2

Products

Libssh2

CVE-2026-57433

Storable versions before 3.41 for Perl have a signed integer overflow when deserializing a crafted SX_HOOK record

Storable versions before 3.41 for Perl have a signed integer overflow when deserializing a crafted SX_HOOK record. retrieve_hook_common reads a signed 32-bit item count from an SX_HOOK record and calls av_extend with that count plus one. A count of I32_MAX wraps the addition to a negative value. A crafted blob passed to thaw or retrieve triggers the overflow; av_extend receives the negative count and dies with a panic, terminating the deserialization.

CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed

Vendors

Haarg Nwclark

Products

Storable Storable

CVE-2026-57432

Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.11 have an integer overflow in S_measure_struct leading to an out-of-bounds heap read in pack and unpack

Perl versions before 5.40.5-RC1, from 5.41.0 before 5.42.3-RC1, from 5.43.0 before 5.43.11 have an integer overflow in S_measure_struct leading to an out-of-bounds heap read in pack and unpack. S_measure_struct adds each item's size times its repeat count to a running total with no overflow check, so a large repeat count in a pack or unpack template wraps the signed SSize_t total negative. The @, X, and x position codes then guard their moves with a signed length comparison that passes when the length is negative, advancing the buffer pointer out of bounds. A template derived from untrusted input can read heap memory past the buffer and return it to the caller.

CVSS 3.1 · 8.4 High EPSS < 1% KEV · Not listed

Vendors

Perl Shay

Products

Perl Perl

CVE-2026-56412

libexpat: libexpat: Use-after-free vulnerability due to improper handling of XML CDATA sections

libexpat before 2.8.2 does not consider XML_TOK_DATA_CHARS in doCdataSection and thus lacks handler call depth tracking for various calls from within handlers in cases of a policy violation. Thus, a use-after-free can occur. NOTE: this issue exists because of an incomplete fix for CVE-2026-50219.

CVSS 3.1 · 4.9 Medium EPSS < 1% KEV · Not listed

Vendors

Libexpat Project

Products

Libexpat

CVE-2026-56411

expat: libexpat: Integer Overflow Vulnerability Leading to Information Disclosure or Code Execution

xmlwf in libexpat before 2.8.2 has an integer overflow in endDoctypeDecl via NOTATION declarations.

CVSS 3.1 · 6.9 Medium EPSS < 1% KEV · Not listed

Vendors

Libexpat Project

Products

Libexpat

CVE-2026-56410

libexpat: libexpat: Integer overflow in xmlwf can lead to information disclosure and arbitrary code execution.

xmlwf in libexpat before 2.8.2 has an integer overflow in resolveSystemId.

CVSS 3.1 · 6.9 Medium EPSS < 1% KEV · Not listed

Vendors

Libexpat Project

Products

Libexpat

CVE-2026-56409

Integer Overflow in libexpat xmlwf Output File Handling

xmlwf in libexpat before 2.8.2 has an integer overflow for the output filename when -d outputDir is used.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Libexpat Project

Products

Libexpat

CVE-2026-56408

Integer Overflow in libexpat copyString Function

libexpat before 2.8.2 has an integer overflow in copyString.

CVSS 3.1 · 6.9 Medium EPSS < 1% KEV · Not listed

Vendors

Libexpat Project

Products

Libexpat

CVE-2026-56407

Integer Overflow in libexpat XML Parser

libexpat before 2.8.2 has an integer overflow in doProlog that is related to storeEntityValue and entity textLen.

CVSS 3.1 · 6.9 Medium EPSS < 1% KEV · Not listed

Vendors

Libexpat Project

Products

Libexpat

CVE-2026-56406

libexpat: libexpat: Arbitrary code execution via integer overflow in XML_ParseBuffer

libexpat before 2.8.2 has an integer overflow in XML_ParseBuffer because it lacked a check that was present in XML_Parse.

CVSS 3.1 · 6.9 Medium EPSS < 1% KEV · Not listed

Vendors

Libexpat Project

Products

Libexpat