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Response snapshot Oct 27, 2026, 02:06 UTC

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VulnerabilityCVE-2026-106116

ImageSharp: BigTIFF IFD count can keep a decoder thread in a non-progressing loop

`SixLabors.ImageSharp` 4.1.1 can spend an attacker-controlled duration decoding a small malformed BigTIFF. The BigTIFF IFD entry-count field is 64-bit. The reader iterates once per declared entry, but when fewer than 20 bytes remain for an entry, the entry read returns without advancing.

At a glance

Exploited
Not known
Severity
5.3 Medium (CVSS 3.1)
Chance of exploitation
0.3% in the next 30 days
Sources
1 source

What to do

GitHub lists first patched versions: SixLabors.ImageSharp: 3.2.0; SixLabors.ImageSharp: 4.1.2. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-wmxv-xphr-5c9g (opens a new tab)

What happened

### Summary

`SixLabors.ImageSharp` 4.1.1 can spend an attacker-controlled duration decoding a small malformed BigTIFF. The BigTIFF IFD entry-count field is 64-bit. The reader iterates once per declared entry, but when fewer than 20 bytes remain for an entry, the entry read returns without advancing. A 24-byte input can therefore run billions of iterations without consuming input.

One decoder invocation occupied one executing thread for more than five seconds in the tested environment. This report makes no worker-pool exhaustion claim.

### Affected package and versions

Continue reading

- Package: `SixLabors.ImageSharp` (NuGet) - Affected range: `>= 2.0.0,

Exe net8.0 enable enable

/root/.nuget/packages/sixlabors.imagesharp/4.1.1/lib/net8.0/SixLabors.ImageSharp.dll

/root/.nuget/packages/system.io.hashing/8.0.0/lib/net8.0/System.IO.Hashing.dll

```

Dockerfile:

```dockerfile FROM mcr.microsoft.com/dotnet/sdk:8.0 WORKDIR /work COPY wmxv.csproj Program.cs ./ RUN printf '%s\n' ' net8.0 ' > fetch.csproj \ && dotnet restore fetch.csproj --nologo \ && rm fetch.csproj \ && dotnet build wmxv.csproj -c Release --nologo -v quiet ENTRYPOINT ["dotnet", "/work/bin/Release/net8.0/wmxv.dll"]

```

Run:

```sh docker build -t imagesharp-wmxv-poc . timeout 5 docker run --rm imagesharp-wmxv-poc 5000000000 docker run --rm imagesharp-wmxv-poc 1 ```

Affected package ranges reported by GitHub: SixLabors.ImageSharp: >= 2.0.0, < 3.2.0 SixLabors.ImageSharp: >= 4.0.0, < 4.1.2

Scores and how they were measured

CVSS base severity

5.3

Version 3.1As of

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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.3%

Scored Percentile 25.8%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-wmxv-xphr-5c9g (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-wmxv-xphr-5c9g, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-106116, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 26). ImageSharp: BigTIFF IFD count can keep a decoder thread in a non-progressing loop (CVE-2026-106116). https://kevwire.com/record/CVE-2026-106116

MLA

"ImageSharp: BigTIFF IFD count can keep a decoder thread in a non-progressing loop (CVE-2026-106116)." KEVWire, 26 Oct. 2026, kevwire.com/record/CVE-2026-106116.

Chicago

KEVWire. "ImageSharp: BigTIFF IFD count can keep a decoder thread in a non-progressing loop (CVE-2026-106116)." Last modified October 26, 2026. https://kevwire.com/record/CVE-2026-106116.

Evidence summary (plain text)

ImageSharp: BigTIFF IFD count can keep a decoder thread in a non-progressing loop (Oct 7, 2026).
`SixLabors.ImageSharp` 4.1.1 can spend an attacker-controlled duration decoding a
small malformed BigTIFF. The BigTIFF IFD entry-count field is 64-bit. The reader
iterates once per declared entry, but when fewer than 20 bytes remain for an entry,
the entry read returns without advancing. A 24-byte input can therefore run billions
of iterations without consuming input.

One decoder invocation occupied one executing thread for more than five seconds in
the tested environment. This report makes no worker-pool exhaustion claim.
CVSS 5.3 (version 3.1; evidence as of Oct 26, 2026; https://github.com/advisories/GHSA-wmxv-xphr-5c9g).
EPSS 0.3% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-106116&date=2026-10-26).
Sources:
GitHub-reviewed advisory GHSA-wmxv-xphr-5c9g: https://github.com/advisories/GHSA-wmxv-xphr-5c9g
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-106116&date=2026-10-26
Record ID: CVE-2026-106116.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 01:40 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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Record details

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