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CVE Record

CVE-2026-32740: libheif: Heap-Buffer-Overflow Write in Grid Tile Chroma Compositing

libheif is a HEIF and AVIF file format decoder and encoder. Versions 1.21.2 and prior contain a heap-buffer-overflow (write) vulnerability in the grid tile compositing, allowing an attacker to write 64 bytes of fully attacker-controlled data past the end of a chroma plane heap allocation by crafting a HEIF/AVIF file with a 1×4 grid of odd-height tiles. The overflow is triggered during normal image decoding with default build configuration. The written bytes are chroma (Cb/Cr) pixel values from the attacking tile, giving the attacker full control over the overflow content. This issue has been fixed in version 1.22.0.

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A malicious HEIF or AVIF image can corrupt memory in libheif during normal decoding. Organizations are exposed where untrusted images are uploaded, previewed, converted, or thumbnailed by software using libheif before version 1.22.0. The vendor reports a fix in 1.22.0.

Executive priority

Treat as a high-priority patching item for internet-facing or customer-facing image processing. The risk is stronger where untrusted images are decoded automatically. No active exploitation is cited in the provided sources, so urgency is high but not KEV-level emergency based on current evidence.

Technical view

CVE-2026-32740 is a CWE-787 heap-buffer-overflow write in libheif grid tile chroma compositing. Crafted 1x4 grids with odd-height tiles can write 64 attacker-controlled chroma bytes beyond a chroma plane allocation during default decoding. Affected versions are below 1.22.0. CVSS is 8.8, high.

Likely exposure

Highest exposure is in services or endpoints that decode untrusted HEIF/AVIF content using libheif below 1.22.0, including upload, preview, conversion, and thumbnailing workflows. Downstream OS packages may carry vendor backports, so package status should be checked rather than relying only on upstream version strings.

Exploitation context

The provided sources do not show active exploitation, and KEV status is false. Exploitation requires processing a crafted image, reflected by CVSS user interaction required. The advisory describes controlled out-of-bounds writes, but the bundle does not prove real-world weaponization or reliable code execution.

Researcher notes

Key validation target is libheif grid tile chroma compositing in versions below 1.22.0. The trigger involves crafted HEIF/AVIF grid structure and odd-height tiles. Avoid assuming downstream products are affected unless they link or package vulnerable libheif and process attacker-supplied files.

Mitigation direction

  • Upgrade libheif to version 1.22.0 or later where feasible.
  • Check distribution or vendor advisories for backported fixes.
  • Prioritize systems that decode externally supplied HEIF or AVIF files.
  • Temporarily restrict untrusted HEIF/AVIF processing until patched.
  • Rebuild dependent applications against the fixed library where needed.

Validation and detection

  • Inventory libheif versions across hosts, containers, and application images.
  • Confirm fixed upstream version 1.22.0 or vendor-fixed package status.
  • Map public upload, preview, conversion, and thumbnailing paths using libheif.
  • Review SBOMs and dependency manifests for bundled libheif copies.
  • Monitor vendor CVE pages for package-specific remediation status.
Prepared
Confidence
high
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-787: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2026-32740 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
6Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: total

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9GitHub_M
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

8.8High
CVSS 3.1 vector shape for CVE-2026-32740Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPlibheif: libheif: Arbitrary code execution or denial of service via crafted HEIF/AVIF file
other:Red Hat severity ratingcvssV3_1
  • 2026-05-19T20:01:03.545Z: Reported to Red Hat.
  • 2026-05-19T19:22:07.743Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
strukturaglibheif< 1.22.0Listed
Weakness

CWE details

CWE-787

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-787 · source CWE mapping

Out-of-bounds Write

Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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