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CVE Record

CVE-2026-40192: Pillow is vulnerable to a FITS GZIP decompression bomb

Pillow is a Python imaging library. Versions 10.3.0 through 12.1.1 did not limit the amount of GZIP-compressed data read when decoding a FITS image, making them vulnerable to decompression bomb attacks. A specially crafted FITS file could cause unbounded memory consumption, leading to denial of service (OOM crash or severe performance degradation). If users are unable to immediately upgrade, they should only open specific image formats, excluding FITS, as a workaround.

HighCVSS 8.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Pillow can be forced to consume excessive memory when it opens a specially crafted GZIP-compressed FITS image. The practical impact is denial of service: an application, worker, or host processing the image may crash or slow severely. The issue affects Pillow 10.3.0 through 12.1.1 and is addressed in 12.2.0.

Executive priority

Treat as a high-priority availability risk for services processing external images. Prioritize internet-facing upload and media-processing systems first, then internal batch pipelines. There is no source-backed evidence of active exploitation in the provided bundle.

Technical view

The FITS decoder in affected Pillow versions did not limit GZIP-compressed data read during image decoding. This enables a decompression bomb condition causing unbounded memory consumption. The CVE is rated high, CVSS 4.0 score 8.7, with CWE-400, CWE-409, and CWE-770 mappings.

Likely exposure

Exposure is most likely in Python applications, services, or batch pipelines using Pillow 10.3.0 through 12.1.1 to process untrusted or externally supplied image files, especially where FITS is accepted or not explicitly blocked.

Exploitation context

The source bundle does not show CISA KEV listing or confirmed active exploitation. The described attack requires a crafted FITS file reaching Pillow’s FITS decoding path. Impact is availability only in the provided CVSS vector.

Researcher notes

Focus validation on Pillow FITS handling and dependency reachability, not just package presence. The public PR, commit, and 12.2.0 release note identify the fix area. Avoid assuming other image formats are affected unless vendor sources expand scope.

Mitigation direction

  • Upgrade Pillow to version 12.2.0 or later.
  • Apply relevant downstream vendor updates, including Red Hat errata where applicable.
  • If upgrade is delayed, allow only required image formats and exclude FITS.
  • Review upload, conversion, and thumbnailing paths that process user-supplied images.
  • Monitor Pillow and OS vendor advisories for any revised guidance.

Validation and detection

  • Inventory direct and transitive Pillow dependencies across applications and containers.
  • Confirm no deployed environment runs Pillow >=10.3.0 and <12.2.0.
  • Check whether image-processing flows accept FITS files from untrusted sources.
  • Verify package updates through lockfiles, images, SBOMs, or runtime dependency reports.
  • For Red Hat systems, map installed packages to the referenced errata or VEX status.
Prepared
Confidence
high
Sources
12

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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-400: 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.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-409: 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.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-770: 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.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-40192 mapping review

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

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
8.7 (4.0)
Known Exploited
No
Published

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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
31Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

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
8.7CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N——GitHub_M
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 4.0 score

8.7High
CVSS 4.0 vector shape for CVE-2026-40192Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
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-SADPPillow: Pillow: Denial of Service via decompression bomb in FITS image processing
other:Red Hat severity ratingcvssV3_1
  • 2026-04-16T00:00:49.590Z: Reported to Red Hat.
  • 2026-04-15T22:53:56.147Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
python-pillowPillow>= 10.3.0, < 12.2.0Listed
Weakness

CWE details

CWE-400CWE-409CWE-770

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

CWE-400 · source CWE mapping

Uncontrolled Resource Consumption

Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-409 · source CWE mapping

Improper Handling of Highly Compressed Data (Data Amplification)

Improper Handling of Highly Compressed Data (Data Amplification) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-770 · source CWE mapping

Allocation of Resources Without Limits or Throttling

Allocation of Resources Without Limits or Throttling represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs