CVE-2026-44638

libsixel: NULL pointer dereference

LOW
2.5
CVSS Score
Published: May 14, 2026 at 07:59 PM UTC
Updated: October 26, 2026 at 02:10 PM UTC
1 product affected across 1 vendorLibsixel

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Severity
LOW2.5
Exploit prediction
EPSS 0.1%
SSVC
PoC

Description

libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From to 1.8.7-r1, a wrong NULL check after an allocation call in sixel_decode_raw and sixel_decode causes a NULL pointer dereference whenever the allocation fails. The check tests the address of the output parameter (always non-NULL) instead of the value the malloc returned. On allocation failure, the function continues and writes through a NULL pointer, crashing the process. This is a denial of service against any caller of these public APIs that hits a low-memory condition. This vulnerability is fixed in 1.8.7-r2.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

1.0.0 ≤ v < 1.8.7-r2
Affected range stops below 1.8.7-r2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (1)

x_refsource_CONFIRMExploitVendor Advisory
Source: cverecord
https://github.com/saitoha/libsixel/security/advisories/GHSA-wpx3-h5g8-qr3w

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

2.5LOWGitHub_M
Attack Vector
LOCAL
Complexity
HIGH
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusANALYZED
CWE
CWE-476CWE-690

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