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CVE Record

CVE-2026-1837: libjxl: Out-of-bounds write in grayscale color transformation when using LCMS2

A specially-crafted file can cause libjxl's decoder to write pixel data to uninitialized unallocated memory. Soon after that data from another uninitialized unallocated region is copied to pixel data. This can be done by requesting color transformation of grayscale images to another grayscale color space. Buffers allocated for 1-float-per-pixel are used as if they are allocated for 3-float-per-pixel. That happens only if LCMS2 is used as CMS engine. There is another CMS engine available (selected by build flags).

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-1837 is a high-severity memory corruption flaw in libjxl 0.9. A crafted image file can cause unsafe memory writes during decoding when LCMS2 handles a grayscale-to-grayscale color conversion. Systems that process untrusted JPEG XL content could face confidentiality, integrity, and availability risk.

Executive priority

Treat this as a priority patch-management and exposure-reduction item for image-processing systems. Urgency is high where untrusted files are decoded automatically, but active exploitation is not confirmed by the supplied sources.

Technical view

The issue is an out-of-bounds write and buffer-size mismatch: buffers sized for one float per pixel are used as three floats per pixel. The condition is tied to grayscale color transformation through LCMS2. CVSS 3.1 is 8.8 with user interaction required and no privileges required.

Likely exposure

Exposure is most likely in applications, services, desktop software, or server pipelines that use libjxl 0.9 to decode externally supplied JPEG XL files with LCMS2 enabled.

Exploitation context

The source bundle describes exploitation through a specially crafted file. KEV is false, and the provided sources do not state active exploitation in the wild or provide a public exploit status.

Researcher notes

The core condition is grayscale-to-grayscale color transformation with LCMS2. Focus validation on code paths invoking libjxl decoding and color conversion, not merely library presence. Evidence is incomplete on fixed versions and downstream package impact.

Mitigation direction

  • Inventory software and containers that include libjxl 0.9.
  • Confirm whether affected builds use LCMS2 as the CMS engine.
  • Check libjxl, Red Hat, and OS vendor guidance for fixed packages or rebuild direction.
  • Limit processing of untrusted JPEG XL files until guidance is applied.
  • If vendor-supported, evaluate builds that do not use LCMS2.

Validation and detection

  • Check dependency manifests and package inventories for libjxl 0.9.
  • Review build flags or package metadata for LCMS2 CMS engine usage.
  • Identify services that decode uploaded, emailed, or web-fetched JPEG XL content.
  • Track vendor advisories for affected package status and remediation availability.
Prepared
Confidence
medium
Sources
6

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-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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cwe · low confidence lookup

CWE-805: 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-2026-1837 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
5Source 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:H2.85.9redhat-SADP
8.7CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N——Google

Vulnerability scoring details

Base CVSS 4.0 score

8.7High
CVSS 4.0 vector shape for CVE-2026-1837Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/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-SADPlibjxl: libjxl: Out-of-bounds write in grayscale color transformation when using LCMS2
other:Red Hat severity ratingcvssV3_1
  • 2026-02-11T16:01:30.361Z: Reported to Red Hat.
  • 2026-02-11T15:19:55.442Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Googlelibjxl0.9unaffected
Weakness

CWE details

CWE-787CWE-805

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.

Open CWE intelligenceSame-CWE CVEs
CWE-805 · source CWE mapping

Buffer Access with Incorrect Length Value

Buffer Access with Incorrect Length Value represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs