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/a0.104.0140FUNC_LEVEL_010410:00:019.1.02:02:002.0.2CMake stabilized (autotools removed); Added db load/compile/free callbacks to clamav.h API.
n/a0.103.4125FUNC_LEVEL_0103_49:05:009.0.52:01:002.0.1Critical bug fixes
Jun-210.103.3124FUNC_LEVEL_0103_39:05:009.0.52:01:002.0.1Critical bug fixes
Apr-210.103.2123FUNC_LEVEL_0103_29:05:009.0.52:01:002.0.1Security fixes
Feb-210.103.1122FUNC_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
Sep-200.103.0120FUNC_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
Jul-200.102.4115FUNC_LEVEL_0102_49:04:009.0.42:00:002.0.0Security fixes
May-200.102.3114FUNC_LEVEL_0102_39:04:009.0.42:00:002.0.0Security fixes
Feb-200.102.2113FUNC_LEVEL_0102_29:04:009.0.42:00:002.0.0Security fixes
Nov-190.102.1112FUNC_LEVEL_0102_19:04:009.0.42:00:002.0.0Security fixes; Significant load time improvement for LDBs with common pattern prefixes
Oct-190.102.0110FUNC_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
Nov-190.101.5106FUNC_LEVEL_0101_59:04:009.0.4Security fixes; Significant load time improvement for LDBs with common pattern prefixes
Aug-190.101.4105FUNC_LEVEL_0101_49:04:009.0.4Security fixes; Added scan time limit, bzip vuln fix
Aug-190.101.3102FUNC_LEVEL_0101_39:03:009.0.3Security fixes; Flevel not incremented (whoops)
Mar-190.101.2102FUNC_LEVEL_0101_29:02:009.0.2Security fixes; Flevel not incremented (whoops)
Jan-190.101.1102FUNC_LEVEL_0101_19:01:009.0.1Fix to clamav.h header; Adds clamav-types.h
Dec-180.101.0100FUNC_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
Mar-190.100.394FUNC_LEVEL_0100_38:02:017.1.2Security fixes
Sep-180.100.293FUNC_LEVEL_0100_28:01:017.1.1Security fixes; Some lenience changes to FreshClam
Jun-180.100.192FUNC_LEVEL_0100_18:01:017.1.1Security fixes; Add support for HTTPS in ClamSubmit
Mar-180.100.090FUNC_LEVEL_01008:01:017.1.1Feature release 2 years in dev't; Many improvements; Notably Container/Intermediates changes; Changes to wildcard signatures
Mar-180.99.485FUNC_LEVEL_099_48:01:017.1.1Security fixes; Other important bug fixes
Jan-180.99.384FUNC_LEVEL_099_38:01:017.1.1Security fixes; Minor bug fixes
May-160.99.282FUNC_LEVEL_099_28:01:017.1.1Various bug fixes
Mar-160.99.182FUNC_LEVEL_099_18:01:017.1.1Security fixes; HWP support
Dec-150.99.081FUNC_LEVEL_0998:01:017.1.1Add Yara and PCRE support; Add 'other' targets type (14) for non-listed target types; Improved on-access scanning.
Apr-150.98.780FUNC_LEVEL_098_77:26:016.1.26Security fixes; MSXML & PDF fixes
Jan-160.98.679FUNC_LEVEL_098_67:25:016.1.25Security fixes; Other bug fixes
Nov-140.98.579FUNC_LEVEL_098_57:22:016.1.22Added internal target type (13); File properties JSON output.
Jun-140.98.477FUNC_LEVEL_098_47:23:016.1.23
May-140.98.377FUNC_LEVEL_098_37:22:016.1.22
May-140.98.277FUNC_LEVEL_098_27:22:016.1.22Add engine_options bit field (and DisableCache option); Add stats callbacks and callback context
Jan-140.98.176FUNC_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)
Sep-130.98.074FUNC_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
Apr-130.97.869FUNC_LEVEL_097_87:17:016.1.17Security fixes
Mar-130.97.768FUNC_LEVEL_097_77:16:016.1.16Security fixes
Sep-120.97.667FUNC_LEVEL_097_67:15:016.1.15Fixed error-handling issues
Jun-120.97.565FUNC_LEVEL_097_57:14:016.1.14First Sourcefire ClamAV release
Mar-120.97.464FUNC_LEVEL_097_47:13:016.1.13Support comment lines in ALL DB files
Oct-110.97.363FUNC_LEVEL_097_37:12:016.1.12
Jul-110.97.262FUNC_LEVEL_097_27:11:016.1.11
Jun-110.97.161FUNC_LEVEL_097_17:10:016.1.10
Feb-110.97.060FUNC_LEVEL_0977:09:016.1.9
Nov-100.96.558FUNC_LEVEL_096_57:07:016.1.7
Oct-100.96.456FUNC_LEVEL_096_47:06:016.1.6Minimal FLEVEL allowed for all current bytecode signatures (quadratic load-time before this point)
Sep-100.96.355FUNC_LEVEL_096_37:05:016.1.5
Aug-100.96.254FUNC_LEVEL_096_27:04:016.1.4
May-100.96.153FUNC_LEVEL_096_17:03:016.1.3
Mar-100.9651FUNC_LEVEL_0967:02:016.1.2Add bytecode & CDB signatures, Ignores should use IGN2 (or take name field only from IGN)
Oct-090.95.3446:05:006.0.5
Jun-090.95.2436:04:006.0.4
Apr-090.95.1426:03:006.0.3
Mar-090.95416:02:006.0.2Ignores should use IGN format (including line number)

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