[CVE-2022-25236] lib: Protect against insertion of namesep characters into namespace URIs #561
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This was referenced Feb 23, 2022
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Feb 28, 2022
Newer version of libexpat have a mitigation for CVE-2022-25236 in place, which disallows the use of certain characters as namespace separators (to my understanding this is the separator used to separate namespace and tag name in the parsed xml output we receive from the library). We implicitly use libexpat via xmltodict.parse(), xmltodict uses a default of ':', which now is invalid. Using ':' as separator results in the following exception: xml.parsers.expat.ExpatError: out of memory: line 1, column 0 This can also be reproduced with this python snippet: xmltodict.parse("<foo></foo>", process_namespaces=True) To mitigate this we need to use a different separator. xmltodict.parse() exposes this as an argument, so passing namespace_separator=' ' (as recommended by libexpat as a char that is not part of an url, see bug reports below or CVE) solves the problem for us. From what I can see this also doesn't require any other changes on our side. Relevant change in libexpat: * libexpat/libexpat#561 Relevant bugreports: * libexpat/libexpat#572 * martinblech/xmltodict#289
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Newer version of libexpat have a mitigation for CVE-2022-25236 in place, which disallows the use of certain characters as namespace separators (to my understanding this is the separator used to separate namespace and tag name in the parsed xml output we receive from the library). We implicitly use libexpat via xmltodict.parse(), xmltodict uses a default of ':', which now is invalid. Using ':' as separator results in the following exception: xml.parsers.expat.ExpatError: out of memory: line 1, column 0 This can also be reproduced with this python snippet: xmltodict.parse("<foo></foo>", process_namespaces=True) To mitigate this we need to use a different separator. xmltodict.parse() exposes this as an argument, so passing namespace_separator=' ' (as recommended by libexpat as a char that is not part of an url, see bug reports below or CVE) solves the problem for us. From what I can see this also doesn't require any other changes on our side. Relevant change in libexpat: * libexpat/libexpat#561 Relevant bugreports: * libexpat/libexpat#572 * martinblech/xmltodict#289
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