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CVE Record

CVE-2026-25646: LIBPNG has a heap buffer overflow in png_set_quantize

LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. Prior to 1.6.55, an out-of-bounds read vulnerability exists in the png_set_quantize() API function. When the function is called with no histogram and the number of colors in the palette is more than twice the maximum supported by the user's display, certain palettes will cause the function to enter into an infinite loop that reads past the end of an internal heap-allocated buffer. The images that trigger this vulnerability are valid per the PNG specification. This vulnerability is fixed in 1.6.55.

HighCVSS 8.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-25646 affects libpng before 1.6.55, a widely used PNG image library. A specially crafted but valid PNG palette can make a vulnerable code path loop and read beyond a heap buffer. The main business risk is disruption in systems that process untrusted PNG files.

Executive priority

Treat as high priority for image-processing services and internet-facing upload workflows. The available evidence supports patching urgency, not emergency incident response, because active exploitation is not shown in the provided sources.

Technical view

The flaw is in png_set_quantize() when called with no histogram and a palette larger than twice the display maximum. Certain valid palettes can trigger an infinite loop and out-of-bounds heap read. Sources list CVSS 4.0 score 8.3 and availability impact as high. It is fixed in libpng 1.6.55.

Likely exposure

Exposure is most likely in applications, libraries, containers, or OS packages using libpng before 1.6.55 and processing untrusted PNGs through the affected quantization API path. Not every libpng consumer is necessarily exposed; API usage matters.

Exploitation context

The bundle does not show CISA KEV listing or cited active exploitation. Exploitation requires specific conditions: vulnerable libpng, the png_set_quantize() path, no histogram, and palette characteristics described by the advisory. Public sources here do not establish weaponized exploitation.

Researcher notes

The vulnerable condition is narrow but reachable with valid PNG files under specific png_set_quantize() usage. Focus analysis on call sites, bundled libpng copies, and downstream vendor backports. The source bundle contains incomplete product-specific exposure details outside libpng and Red Hat advisories.

Mitigation direction

  • Upgrade libpng to 1.6.55 or later where directly managed.
  • Apply vendor-patched OS packages, including relevant Red Hat errata where applicable.
  • Check distribution advisories for backported fixes and package-specific status.
  • Prioritize services that accept PNG uploads or process external images.
  • Retire or rebuild containers carrying vulnerable libpng versions.

Validation and detection

  • Inventory libpng versions across hosts, containers, and bundled application dependencies.
  • Confirm whether applications call png_set_quantize() on untrusted PNG input.
  • Verify patched packages map to vendor advisories or libpng 1.6.55.
  • Review SBOMs and image-processing dependencies for embedded libpng copies.
  • Document any non-exposed systems where the affected API path is unused.
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-122: 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-125: 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-126: 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-2026-25646 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
8.3 (4.0)
Known Exploited
No
Published

Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/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
3ADP providers
43Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: noTechnical 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
8.3CVSS 4.0HighCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N——GitHub_M
7CVSS 3.1HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H2.24.7redhat-SADP

Vulnerability scoring details

Base CVSS 4.0 score

8.3High
CVSS 4.0 vector shape for CVE-2026-25646Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/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

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPlibpng: LIBPNG has a heap buffer overflow in png_set_quantize
other:Red Hat severity ratingcvssV3_1
  • 2026-02-10T18:01:28.232Z: Reported to Red Hat.
  • 2026-02-10T17:04:38.501Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
pnggrouplibpng< 1.6.55Listed
Weakness

CWE details

CWE-122CWE-125CWE-126

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

CWE-122 · source CWE mapping

Heap-based Buffer Overflow

Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-125 · source CWE mapping

Out-of-bounds Read

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

Open CWE intelligenceSame-CWE CVEs
CWE-126 · source CWE mapping

Buffer Over-read

Buffer Over-read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs