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Out-of-bounds WriteWeakness · CWE-787

CVE-2026-40493

CRITICAL · 9.8 CVSS v3.1 Published 2026-04-18
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
SAIL is a cross-platform library for loading and saving images with support for animation, metadata, and ICC profiles. Prior to commit c930284445ea3ff94451ccd7a57c999eca3bc979, the PSD codec computes bytes-per-pixel (`bpp`) from raw header fields `channels * depth`, but the pixel buffer is allocated based on the resolved pixel format. For LAB mode with `channels=3, depth=16`, `bpp = (3*16+7)/8 = 6`, but the format `BPP40_CIE_LAB` allocates only 5 bytes per pixel. Every pixel write overshoots, causing a deterministic heap buffer overflow on every row. Commit c930284445ea3ff94451ccd7a57c999eca3bc979 contains a patch.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The SAIL library's PSD codec has a heap buffer overflow in LAB color mode processing. When handling LAB mode PSDs with 3 channels and 16-bit depth, the code calculates 6 bytes-per-pixel (bpp = (3*16+7)/8), but the BPP40_CIE_LAB format only allocates 5 bytes per pixel, causing a deterministic 1-byte overflow on every pixel write.

MitigationUpdate SAIL to version c930284445ea3ff94451ccd7a57c999eca3bc979 or later which contains the fix. If unable to update, avoid loading untrusted PSD files in LAB color mode.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify SAIL library installation
    Search for lib sail or sail DLL in the system: on Linux run 'find /usr -name "*sail*" 2>/dev/null' or check package manager; on Windows search for sail.dll
    Affected if SAIL library files are found in the system
  2. Check installed SAIL version
    If version information is embedded in the library binary, use 'strings' to search for version strings: 'strings [library_path] | grep -i version' or check build metadata if available
    Affected if Version is unknown or earlier than c930284445ea3ff94451ccd7a57c999eca3bc979
  3. Identify PSD file processing
    Review application logs, code, or runtime behavior to confirm the application uses SAIL to decode PSD files
    Affected if Application loads and decodes PSD files using SAIL
  4. Verify LAB mode 3-channel 16-bit PSD handling
    Inspect PSD files being processed or check if the application code path for LAB color mode with 3 channels at 16-bit depth is reachable
    Affected if PSD files in LAB color mode with 3 channels at 16-bit depth are processed

The environment is affected if SAIL library version is present and processes PSD files in LAB color mode with 3 channels at 16-bit depth.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Interim mitigation

Update SAIL to version c930284445ea3ff94451ccd7a57c999eca3bc979 or later which contains the fix. If unable to update, avoid loading untrusted PSD files in LAB color mode.

Recommended fix Moderate confidence

Any release or commit after c930284445ea3ff94451ccd7a57c999eca3bc979

  1. 1. Navigate to the SAIL library repository: https://github.com/HappySeaFox/sail
  2. 2. Locate the PSD codec source file containing the pixel buffer allocation logic
  3. 3. Apply the fix from commit c930284445ea3ff94451ccd7a57c999eca3bc979, which corrects the bytes-per-pixel calculation to match the actual allocated buffer size for LAB mode images
  4. 4. Recompile the library with the patched code
  5. 5. Verify the fix resolves the buffer overflow by testing PSD file loading with LAB color mode (3 channels, 16-bit depth)

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,800
Get the patch applied

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,080.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-40493 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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