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CVE-2026-26740: Buffer Overflow vulnerability in giflib v.5.2.2 allows a remote attacker to cause a denial of service via t...

Buffer Overflow vulnerability in giflib v.5.2.2 allows a remote attacker to cause a denial of service via the EGifGCBToExtension overwriting an existing Graphic Control Extension block without validating its allocated size.

HighCVSS 8.2Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-26740 is a high-severity giflib 5.2.2 memory overwrite flaw. A remote attacker could trigger a denial of service when vulnerable software processes crafted GIF data. Business impact is most relevant for services that automatically ingest, transform, or analyze GIF images.

Executive priority

Prioritize remediation for public-facing or automated GIF-processing systems. For general workstations or systems not handling untrusted GIFs, schedule through normal high-severity patch cycles after confirming exposure.

Technical view

The issue is a CWE-787 out-of-bounds write in EGifGCBToExtension. It can overwrite an existing Graphic Control Extension block without validating allocated size. The provided CVSS 3.1 score is 8.2, with network attack vector, no privileges, no user interaction, low integrity impact, and high availability impact.

Likely exposure

Systems are most exposed if they include giflib 5.2.2 or Red Hat packages covered by the listed RHSA advisories, especially internet-facing upload, thumbnailing, conversion, or content-processing workflows that handle GIF files.

Exploitation context

The source bundle includes a public GitHub proof-of-concept/disclosure reference. CISA KEV status is false, and no provided source states active exploitation. Treat exploitation as plausible where untrusted GIF processing reaches vulnerable giflib code.

Researcher notes

Affected product metadata in the bundle is incomplete, but the description identifies giflib 5.2.2. Red Hat has multiple advisory references. The public PoC reference increases validation urgency, but provided sources do not establish in-the-wild exploitation.

Mitigation direction

  • Inventory systems, containers, and applications that include giflib.
  • Check Red Hat RHSA advisories for applicable updated packages.
  • Apply vendor-provided updates where available.
  • If no fix is available, limit processing of untrusted GIF files.
  • Reduce exposure of image-processing services to unauthenticated uploads.

Validation and detection

  • Confirm whether giflib 5.2.2 is present in hosts or containers.
  • Map installed Red Hat packages to the referenced RHSA advisories.
  • Review SBOMs for bundled or statically linked giflib copies.
  • Verify image-processing paths that accept GIF input.
  • Confirm patched package status through approved vulnerability scanning.
Prepared
Confidence
medium
Sources
9

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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cve · low confidence lookup

CVE-2026-26740 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
8.2 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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
18Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: 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
8.2CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H3.94.2CISA-ADP
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 3.1 score

8.2High
CVSS 3.1 vector shape for CVE-2026-26740Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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
cvssV3_1other:ssvc
redhat-SADPgiflib: giflib: Denial of Service via buffer overflow in EGifGCBToExtension
other:Red Hat severity ratingcvssV3_1
  • 2026-03-18T19:01:41.415Z: Reported to Red Hat.
  • 2026-03-18T00:00:00.000Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
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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