Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

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Walter_Kacynski's avatar
Walter_Kacynski
Icon for Cirrostratus rankCirrostratus
Jun 27, 2017

ASM failed to convert character unicode

Does anyone know how the ASM uft-8 metadata character conversion process works? I have a situation where a user submits unicode U+2019 (http://www.fileformat.info/info/unicode/char/2019/index.htm). However ASM doesn't seem to handle this particular meta character. The only solution is to disable character set checking.

 

1 Reply

  • Ashwin_Venkat's avatar
    Ashwin_Venkat
    Icon for Employee rankEmployee
    Jun 28, 2017

    Unicode U+2019 is referred to as 'right single quotation mark': https://www.compart.com/en/unicode/U+2019 and that one percent encodes to %92 per the ASCII table: http://www.ascii-code.com/. This one isn't considered to be unicode, if the application encoding language used by the ASM policy is UTF+8. As a result of this, when ASM gets the percent encoded request and tries to decode %92, it isn't able to do it for this application language. This results in the "Failed to convert character" violation.

     

    Recommendation would be to use a different application language or to continue having the blocking setting disabled for this violation.