Impact:
Incorrect Timezone value.

Reproduction:
The issue can be reproduced on AIX using the following standalone Java program:

public class TZCheck {
  public static void main(String[] args) {
    System.out.println("Default TZ: " + java.util.TimeZone.getDefault());
  }
}

export TZ=CET-1CEST,M3.5.0,M10.5.0


Expected :
Default TZ: sun.util.calendar.ZoneInfo[id="Europe/Paris",offset=3600000,dstSavings=3600000,useDaylight=true,transitions=184,lastRule=java.util.SimpleTimeZone[id=Europe/Paris,offset=3600000,dstSavings=3600000,useDaylight=true,startYear=0,startMode=2,startMonth=2,startDay=-1,startDayOfWeek=1,startTime=3600000,startTimeMode=2,endMode=2,endMonth=9,endDay=-1,endDayOfWeek=1,endTime=3600000,endTimeMode=2]]

Actual :
Default TZ: sun.util.calendar.ZoneInfo[id="GMT+01:00",offset=3600000,dstSavings=0,useDaylight=false,transitions=0,lastRule=null]

Affected File:
src/java.base/unix/native/libjava/TimeZone_md.c