Use after free in Saitoha Libsixel
CVSS score
7.3
EPSS probability
%0.2
Risk score
0.0
Published
6 mo ago
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Vulnerability description
DayBreach CVE AI Research
CVE-2026-33021 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.
libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain a use-after-free vulnerability in sixel_encoder_encode_bytes() because sixel_frame_init() stores the caller-owned pixel buffer pointer directly in frame->pixels without making a defensive copy. When a resize operation is triggered, sixel_frame_convert_to_rgb888() unconditionally frees this caller-owned buffer and replaces it with a new internal allocation, leaving the caller with a dangling pointer. Any subsequent access to the original buffer by the caller constitutes a use-after-free, confirmed by AddressSanitizer. An attacker who controls incoming frames can trigger this bug repeatedly and predictably, resulting in a reliable crash with potential for code execution. This issue has been fixed in version 1.8.7-r1.
IMPACT: Affected Products and Software
Affected Products
The following products are affected by CVE-2026-33021 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.
| ID | VENDOR | PRODUCT | ACTION |
|---|---|---|---|
| 1 | saitoha | libsixel | View |
RED HAT CSAF/VEX: Product Impact Check
SCORING: CVSS from Multiple Sources
CVSS Scores
The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.
| SCORE | VERSION | SEVERITY | VECTOR | SOURCE |
|---|---|---|---|---|
| 7.3 | CVSS V31 | HIGH | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H | NVD |
Patch and Remediation Guide
Solution & Remediation Advisory
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Public exploit and active exploitation status
Verified exploit intelligence
CVE-2026-33021 : the database holds 1 public PoC/exploit sources for it. For direct links to the sources, open the Public Exploits tab.
Weakness Classification and Attack Patterns (CWE & CAPEC)
CWE - Common Weakness Enumeration
While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-33021 is associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-33021 weaknesses.
Attack Vector and Accessibility
Official Sources and Advisories
Similar Vulnerabilities
libsixel before 1.8.7-r1 and 1.9.0 through 1.10.5 Heap Out-of-Bounds Write via GIF
Use after free in Saitoha Libsixel
Integer overflow in Saitoha Libsixel
Out-of-bounds read in Saitoha Libsixel
Use after free in Saitoha Libsixel
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