Adobe Systems warned users Tuesday that an unpatched Flash Player vulnerability is currently being exploited in targeted attacks. The company expects to deliver a patch as soon as Thursday.

The exploit was discovered by researchers from antivirus vendor Kaspersky Lab in attacks attributed to a cyberespionage group known in the security industry as ScarCruft.

The group is relatively new, but is apparently quite resourceful, as this is possibly the second zero-day -- previously unknown and unpatched -- exploit that it used this year.

The other exploit targeted a critical remote code execution vulnerability in Microsoft XML Core Services that was tracked as CVE-2016-0147 and was patched by Microsoft in April.

ScarCruft has been exploiting the new Flash Player zero-day flaw, which Adobe tracks as CVE-2016-4171, as part of a cyberespionage campaign against high-profile victims that was launched in March.

Kaspersky Lab has dubbed this campaign Operation Daybreak and has detected victims in Russia, Nepal, South Korea, China, India, Kuwait and Romania.

ScarCruft is also behind a separate cyberespionage campaign dubbed Operation Erebus that exploits a critical vulnerability in Flash Player patched in May. That vulnerability was also a zero-day when it was discovered in the wild by researchers from security vendor FireEye.

In a security advisory published Tuesday, Adobe said that it will address the new vulnerability in its monthly security bulletins, which will be available as early as Thursday.

Meanwhile, the Kaspersky Lab researchers have confirmed that Microsoft's Enhanced Mitigation Experience Toolkit (EMET) blocks the attack so companies should consider using this tool on their endpoint systems, if they aren't already.