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N A EUVDEUVD-2026-12914

| CVE-2026-26740 HIGH
Out-of-bounds Write (CWE-787)
2026-03-18 mitre
Buffer Overflow Denial Of Service Memory Corruption N A
8.2
CVSS 3.1 · Vendor: mitre
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Send crafted GIF file with malformed Graphic Control Extension
  2. Exploit
    Parser calls EGifGCBToExtension without size validation
  3. Execution
    Buffer overflow overwrites adjacent memory
  4. Impact
    Denial of service or data corruption occurs

Vulnerability Assessment

Weakness
CWE
CWE-787
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, write limits
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Exploitation Conditions

Victim must process a crafted GIF file containing a malformed Graphic Control Extension block using giflib v.5.2.2. Remote attacker can deliver the malicious GIF via network (email, web download, etc.) or local file. No authentication required. Victim interaction: opening/processing the GIF file.
Impact

Despite the absence of a formal CVSS vector and EPSS score, multiple risk indicators suggest this is a genuine but contained threat. The vulnerability is remotely exploitable (attack vector: network) and requires no authentication, but exploitation is limited to denial of service rather than code execution or data exfiltration. The existence of a publicly available proof-of-concept on GitHub significantly lowers the barrier to exploitation and indicates active research interest. However, the lack of KEV (Known Exploited Vulnerability) designation and absence of reports of in-the-wild exploitation suggest this has not yet become a widespread active threat. The vulnerability affects a library component rather than user-facing applications, meaning risk depends on how many downstream products integrate giflib and whether those products process untrusted GIF input from network sources. This is a priority for developers and vendors who bundle giflib, but the real-world impact will vary by deployment context. Organizations should treat this as medium-to-high priority for patching rather than critical.
Exploit ScenarioDerived

An attacker crafts a malicious GIF file with a specially sized Graphic Control Extension block that violates memory allocation assumptions in the EGifGCBToExtension function. When a vulnerable application (e.g., an image processing server or automated thumbnail generator) attempts to process the GIF, the buffer overflow is triggered, causing heap corruption and an application crash. A publicly available POC, such as the one referenced in the GitHub repository, lowers the technical barrier for an attacker to execute this attack repeatedly against exposed services, enabling a relatively simple denial-of-service campaign against websites or services that accept GIF uploads.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 18, 2026

Giflib 5.2.2 contains a buffer overflow in the EGifGCBToExtension function that fails to validate allocated memory when processing Graphic Control Extension blocks, enabling remote attackers to trigger denial of service conditions. Public exploit code exists for this vulnerability, though no patch is currently available. The flaw affects any application using the vulnerable giflib version to process GIF files from untrusted sources.

Earlier versions of this analysis (1)
v1 Mar 18, 2026 - 18:15 CVSS 8.2

A buffer overflow vulnerability exists in giflib version 5.2.2 within the EGifGCBToExtension function, which fails to validate allocated size when overwriting an existing Graphic Control Extension block in GIF files. This allows a remote attacker to trigger a denial of service condition by crafting a malicious GIF file. A proof-of-concept exploit is publicly available on GitHub, increasing real-world risk despite the absence of formal CVSS scoring and EPSS data.

RemediationAI

Upgrade giflib to version 5.2.3 or later (refer to the official giflib repository at https://github.com/jhalley/giflib for patched releases). For applications unable to upgrade immediately, implement input validation by rejecting or sandboxing untrusted GIF files, and monitor for application crashes or unexpected exits when processing GIF input. Deploy network-based protections to restrict GIF file uploads to trusted sources only. If giflib is embedded in a third-party application, contact the vendor for an updated build that includes patched giflib dependencies. Automated dependency scanning tools should flag any remaining installations of giflib versions prior to 5.2.3.

Affected VersionsENISA

n/a n/a

Affects your stack

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Technical ContextAI · show details

Giflib is a widely-used C library for reading and writing GIF image files, commonly integrated into image processing tools, web servers, and multimedia applications. The vulnerability resides in the EGifGCBToExtension function, which handles Graphic Control Extension (GCE) blocks—metadata structures in GIF files that define animation timing and transparency. The root cause is insufficient bounds checking (CWE-120: Buffer Copy without Checking Size of Input) when the function overwrites existing GCE blocks without verifying that the destination buffer has sufficient allocated memory. When processing a specially crafted GIF, an attacker can write beyond buffer boundaries, corrupting heap memory and triggering a crash or undefined behavior. The affected product is giflib (identified in CPE nomenclature, though vendor-neutral CPE strings suggest broad applicability across multiple downstream consumers).

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Severity by source

Vendor (mitre) PRIMARY 8.2 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
SUSE HIGH
Red Hat 7.5 HIGH

Primary rating from Vendor (mitre).

CVSS VectorVendor: mitre

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High

Lifecycle Timeline

3
Patch released
Apr 10, 2026 - 08:30 nvd
Patch available
PoC Detected
Mar 21, 2026 - 00:09 vuln.today
Public exploit code
CVE Published
Mar 18, 2026 - 00:00 nvd
HIGH 8.2

DescriptionCVE.org

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.

Executive ViewAI

Why It Matters

Organizations using Buffer Overflow vulnerability in giflib v.5.2.2 face notable risk from CVE-2026-26740, a out-of-bounds write vulnerability rated CVSS 8.2. Exploitation could allow attackers to corrupt memory, crash the application, or potentially execute arbitrary code. Proof-of-concept code is publicly available, increasing the risk of exploitation. Organizations should apply vendor updates when available and consider compensating controls in the interim.

Business Impact: High
Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Enable ASLR and DEP where available; (2) Implement network segmentation; (3) Monitor for exploitation indicators.

Threat Intelligence Overview

EPSS Score
0.1%
Top 73% exploitable
Exploit
POC
Public exploit code exists
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vendor GitHub VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC Yes
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Out-of-Cycle
Exploitation· derived
Poc
System Exposure· derived
Open
Automatable· derived
Yes
Human Impact
High

Priority Score

61
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +41
PoC: +20
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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Same weakness CWE-787 – Out-of-bounds Write

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CVE-2014-1761 HIGH POC
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CVE-2009-3129 HIGH POC
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CVE-2021-1732 HIGH POC
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Same technique Buffer Overflow

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Vendor StatusVendor

SUSE

Severity: High
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Module for Basesystem 15 SP7 Fixed
SUSE Linux Enterprise Server 15 SP7 Fixed
SUSE Linux Enterprise Server 16.0 Fixed

References

Advisories & patches
ADVISORY http://chromereleases.googleblog.com/2026/05/stable-channel-update-for-chromeos_01312344978.html ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-26740 ADVISORY https://vuldb.com/?id.351589 REF https://access.redhat.com/errata/RHSA-2026:33447 REF https://access.redhat.com/errata/RHSA-2026:33450 REF https://access.redhat.com/errata/RHSA-2026:33451 REF https://access.redhat.com/errata/RHSA-2026:33452 REF https://access.redhat.com/errata/RHSA-2026:33455 REF https://access.redhat.com/errata/RHSA-2026:33456 REF https://access.redhat.com/errata/RHSA-2026:33501 REF https://access.redhat.com/errata/RHSA-2026:33502 REF https://access.redhat.com/errata/RHSA-2026:33503 REF https://access.redhat.com/errata/RHSA-2026:33509 REF https://access.redhat.com/errata/RHSA-2026:36004 REF https://access.redhat.com/errata/RHSA-2026:36005 REF https://access.redhat.com/errata/RHSA-2026:36006 REF https://access.redhat.com/errata/RHSA-2026:9683 REF https://access.redhat.com/errata/RHSA-2026:9686 REF https://access.redhat.com/errata/RHSA-2026:9689 REF https://access.redhat.com/errata/RHSA-2026:9693 REF https://access.redhat.com/security/cve/CVE-2026-26740 REF https://bugzilla.redhat.com/show_bug.cgi?id=2448747 REF https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-26740.json

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