| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| Expat before 2.8.5 fails to validate that a high surrogate in UTF-16 input is followed by a low surrogate, allowing malformed UTF-16 sequences to be accepted. Attackers can supply UTF-16 encoded XML containing lone high surrogates that consume the following code unit, causing Expat to pass unpaired surrogates to applications built with XML_UNICODE and to silently replace input characters in other builds. |
| 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. |
| 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. |
| 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. |
| 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. |
| 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. |
| xmlwf in libexpat before 2.8.2 has an integer overflow in endDoctypeDecl via NOTATION declarations. |
| xmlwf in libexpat before 2.8.2 has an integer overflow in resolveSystemId. |
| xmlwf in libexpat before 2.8.2 has an integer overflow for the output filename when -d outputDir is used. |
| libexpat before 2.8.2 has an integer overflow in copyString. |
| libexpat before 2.8.2 has an integer overflow in doProlog that is related to storeEntityValue and entity textLen. |
| libexpat before 2.8.2 has an integer overflow in XML_ParseBuffer because it lacked a check that was present in XML_Parse. |
| libexpat before 2.8.2 has an integer overflow in getAttributeId. |
| libexpat before 2.8.2 has an integer overflow in addBinding. |
| libexpat before 2.8.2 has an integer overflow in storeAtts. |
| In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold backing array reallocation is mishandled when there is data-structure sharing across parsers. |
| libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_ResumeParser from within handlers in cases of a policy violation. Thus, a use-after-free can occur (similar to the CVE-2026-50219 situation). |
| libexpat before 2.8.2 lacks handler call depth tracking for calls to XML_GetBuffer, XML_Parse, XML_ParseBuffer, XML_ParserFree, or XML_ParserReset from within handlers in cases of a policy violation. Thus, a use-after-free can occur, |
| In libexpat before 2.8.1, the computational complexity of attribute name collision checks allows a denial of service via moderately sized crafted XML input. |
| libexpat before 2.7.5 allows a NULL pointer dereference in the function setContext on retry after an earlier ouf-of-memory condition. |
