Disclosure summary
### Summary A malformed embedded ICC profile can make ImageSharp allocate memory from attacker-controlled CLUT channel and grid dimensions before verifying that the declared CLUT values are present. In published v1 through v3 packages, the public lazy ICC parser allocates approximately 115 MB from the 200-byte test profile before rejecting the truncated tag. In published v4 packages, decoding with ICC conversion enabled requests an 860,934,420-byte managed float array from the same profile. ### Affected package and versions - Package: `SixLabors.ImageSharp` (NuGet) - Affected range: `>= 1.0.0-beta0001, = 4.0.0, BinaryPrimitives.WriteUInt32BigEndian(bytes.AsSpan(offset, 4), value); private static void U16(byte[] bytes, int offset, ushort value) => BinaryPrimitives.WriteUInt16BigEndian(bytes.AsSpan(offset, 2), value); private static void Ascii(byte[] bytes, int offset, string value) { for (int i = 0; i < value.Length; i++) bytes[offset + i] = (byte)value[i]; } // ICC v4 RGB profile containing an A2B0 mpet tag whose CLUT is deliberately // truncated after its grid descriptor. ReadClutF32 still sizes float[] from // the 15 untrusted input/output channels and the grid value of three. pr
Source-specific records & product guidance
Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.
GitHub Reviewed Security Advisories · GHSA-gwg2-r3hj-4w44
Open original source · Updated Oct 07, 2026
ImageSharp: ICC CLUT parsing allocates from unvalidated channel and grid dimensions
Source severity: MEDIUM / 0
| Ecosystem | Package | Affected range | First patched |
|---|---|---|---|
| nuget | SixLabors.ImageSharp | >= 1.0.0-beta0001, | 4.1.2 |
Original records & references
- NIST NVD record
- CVE Program record
- github.com — Reviewed advisory
PUBLISHED 2026-10-07T16:24:19-04:00
MODIFIED 2026-10-07T16:24:19-04:00
INGESTED 2026-10-08T12:30:39-04:00