Versions & Functionality Levels (FLEVELs)

The Functionality Level (or FLEVEL) is an integer that signatures may use to define which versions of ClamAV the signature features support. It is up to the signature writers to select the correct FLEVEL or range of FLEVELs when writing a signature so that it does not cause failures in older versions of ClamAV.

Setting appropriate FLEVELs in signatures is particularly crucial when using features added in the last 3-4 major release versions.

ClamAV Version to FLEVEL chart

Note: This markdown table is generated from a spreadsheet using this tool.

Release DateReleaseFLEVELFunctionalityLevel (bytecode enum)clamav lib.sofreshclam lib.soAPI/ABI changes, major features, other notes
n/a0.104.0130FUNC_LEVEL_0104CMake stabilized (autotools deprecated)
n/a0.103.4125FUNC_LEVEL_0103_49:05:009.0.52:01:002.0.1Critical bug fixes
2021-060.103.3124FUNC_LEVEL_0103_39:05:009.0.52:01:002.0.1Critical bug fixes
2021-040.103.2123FUNC_LEVEL_0103_29:05:009.0.52:01:002.0.1Security fixes
2021-020.103.1122FUNC_LEVEL_0103_19:05:009.0.52:01:002.0.1Fix PNG parser; Loosen GIF format validation (trailer byte); Fix scan issue on Windows RAM disks; Fix clamonacc FD-passing; Enable JPEG & TIFF validation; Add CL_TYPE_JPEG, CL_TYPE_TIFF; Adds ALERT_BROKEN_IMAGES scan heuristics option
2020-080.103.0121FUNC_LEVEL_01039:05:009.0.52:01:002.0.1Add CL_TYPE_PNG, CL_TYPE_GIF; Add XLM macro detection; Add bzip2 & LZMA decompression functions to bytecode API
2020-070.102.4115FUNC_LEVEL_0102_49:04:009.0.42:00:002.0.0Security fixes
2020-050.102.3114FUNC_LEVEL_0102_39:04:009.0.42:00:002.0.0Security fixes
2020-020.102.2113FUNC_LEVEL_0102_29:04:009.0.42:00:002.0.0Security fixes
2019-110.102.1112FUNC_LEVEL_0102_19:04:009.0.42:00:002.0.0Security fixes; Significant load time improvement for LDBs with common pattern prefixes
2019-100.102.0111FUNC_LEVEL_01029:04:009.0.42:00:002.0.0BytecodeKind: BC_ELF_UNPACKER, BC_MACHO_UNPACKER; Add CL_TYPE_EGG/CL_TYPE_EGG_SFX; Added scan time limit
2019-110.101.5106FUNC_LEVEL_0101_59:04:009.0.4Security fixes; Significant load time improvement for LDBs with common pattern prefixes
2019-080.101.4105FUNC_LEVEL_0101_49:04:009.0.4Security fixes; Added scan time limit, bzip vuln fix
2019-080.101.3102FUNC_LEVEL_0101_39:03:009.0.3Security fixes; Flevel not incremented (whoops)
2019-030.101.2102FUNC_LEVEL_0101_29:02:009.0.2Security fixes; Flevel not incremented (whoops)
2019-010.101.1102FUNC_LEVEL_0101_19:01:009.0.1Fix to clamav.h header; Adds clamav-types.h
2018-120.101.0101FUNC_LEVEL_01019:00:009.0.0Non-backwards compatible API/ABI change: Added filename to scanfile & scandesc, and scan options became a struct; RAR5 Support; Byte-Compare Subsigs; Add CL_TYPE_LNK
2019-030.100.394FUNC_LEVEL_0100_38:02:017.1.2Security fixes
2018-090.100.293FUNC_LEVEL_0100_28:01:017.1.1Security fixes; Some lenience changes to FreshClam
2018-060.100.192FUNC_LEVEL_0100_18:01:017.1.1Security fixes; Add support for HTTPS in ClamSubmit
2018-030.100.091FUNC_LEVEL_01008:01:017.1.1Feature release 2 years in dev't; Many improvements; Notably Container/Intermediates changes; Changes to wildcard signatures
2018-030.99.485FUNC_LEVEL_099_48:01:017.1.1Security fixes; Other important bug fixes
2018-010.99.384FUNC_LEVEL_099_38:01:017.1.1Security fixes; Minor bug fixes
2016-050.99.282FUNC_LEVEL_099_28:01:017.1.1Various bug fixes
2016-030.99.182FUNC_LEVEL_099_18:01:017.1.1Security fixes; HWP support
2015-120.99.081FUNC_LEVEL_0998:01:017.1.1Add Yara and PCRE support; Add 'other' targets type (14) for non-listed target types; Improved on-access scanning.
2015-040.98.780FUNC_LEVEL_098_77:26:016.1.26Security fixes; MSXML & PDF fixes
2016-010.98.679FUNC_LEVEL_098_67:25:016.1.25Security fixes; Other bug fixes
2014-110.98.579FUNC_LEVEL_098_57:22:016.1.22Added internal target type (13); File properties JSON output.
2014-060.98.477FUNC_LEVEL_098_47:23:016.1.23
2014-050.98.377FUNC_LEVEL_098_37:22:016.1.22
2014-050.98.277FUNC_LEVEL_098_27:22:016.1.22Add engine_options bit field (and DisableCache option); Add stats callbacks and callback context
2014-010.98.176FUNC_LEVEL_098_17:20:016.1.20Added XZ support and ForceToDisk scan option; Added Libxml2 dependency + XAR, DMG, HFS+/HFSX support; Added FTM type 4 (for in-buffer partition magic, analogous to type 0 for files)
2013-090.98.074FUNC_LEVEL_0987:18:016.1.18Add Target-Types 10 - 13 (PDF, FLASH, JAVA, and INTERNAL); Introduced all-scan options; SWF and Java targets (11 & 12); Introduced with "SE" offset modifier; Introduced with ISO9660 scanning support; Add wild card bracket notation{} for body-based signatures; Disable SWF parser
2013-040.97.869FUNC_LEVEL_097_87:17:016.1.17Security fixes
2013-030.97.768FUNC_LEVEL_097_77:16:016.1.16Security fixes
2012-090.97.667FUNC_LEVEL_097_67:15:016.1.15Fixed error-handling issues
2012-060.97.565FUNC_LEVEL_097_57:14:016.1.14First Sourcefire ClamAV release
2012-030.97.464FUNC_LEVEL_097_47:13:016.1.13Support comment lines in ALL DB files
2011-100.97.363FUNC_LEVEL_097_37:12:016.1.12
2011-070.97.262FUNC_LEVEL_097_27:11:016.1.11
2011-060.97.161FUNC_LEVEL_097_17:10:016.1.10
2011-020.97.060FUNC_LEVEL_0977:09:016.1.9
2010-110.96.558FUNC_LEVEL_096_57:07:016.1.7
2010-100.96.456FUNC_LEVEL_096_47:06:016.1.6Minimal FLEVEL allowed for all current bytecode signatures (quadratic load-time before this point)
2010-090.96.355FUNC_LEVEL_096_37:05:016.1.5
2010-080.96.254FUNC_LEVEL_096_27:04:016.1.4
2010-050.96.153FUNC_LEVEL_096_17:03:016.1.3
2010-030.9651FUNC_LEVEL_0967:02:016.1.2Add bytecode & CDB signatures, Ignores should use IGN2 (or take name field only from IGN)
2009-100.95.3446:05:006.0.5
2009-060.95.2436:04:006.0.4
2009-040.95.1426:03:006.0.3
2009-030.95416:02:006.0.2Ignores should use IGN format (including line number)

For more information on ClamAV file type support, see the File Types Reference.