libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain a Use-After-Free vulnerability via the load_gif() function in fromgif.c, where a single sixel_frame_t object is reused across all frames of an animated GIF and gif_init_frame() unconditionally frees and reallocates frame->pixels between frames without consulting the object's reference count. Because the public API explicitly provides sixel_frame_ref() to retain a frame and sixel_frame_get_pixels() to access the raw pixel buffer, a callback following this documented usage pattern will hold a dangling pointer after the second frame is decoded, resulting in a heap use-after-free confirmed by ASAN. Any application using sixel_helper_load_image_file() with a multi-frame callback to process user-supplied animated GIFs is affected, with a reliable crash as the minimum impact and potential for code execution. This issue has been fixed in version 1.8.7-r1.
Conclusion & alert: CVE-2026-33018 is rated Exploit Available (50/100): CVSS High severity, with low exploitation likelihood (EPSS 0.19%). Core evidence: 1 public exploit reference(s) are indexed (Exploit-DB). Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
| EDB-ID | Source | Kind | Published | Link |
|---|---|---|---|---|
| — | nvd_ref | exploit_tag | Exploit-DB ↗ |
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.01% | 0.19% | +0.18% |
| 2 | 2026-04-15 | — | 0.01% | — |
Full EPSS history (2 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 7.0 | 3.1 | HIGH |
|
1.0 | 5.9 | [email protected] |
| vendor | priority | summary | link |
|---|---|---|---|
debian
|
not yet assigned | CVE-2026-33018 not yet assigned priority: Debian including 1 source packages (libsixel), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. | https://security-tracker.debian.org/tracker/CVE-2026-33018 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2026-33018 |
suse
|
high | — | https://www.suse.com/security/cve/CVE-2026-33018/ |
ubuntu
|
medium | CVE-2026-33018 medium priority: Ubuntu including 1 source packages (libsixel), 7 status rows across 7 suites (bionic, focal, jammy, noble, questing, upstream, xenial): needs-triage 7. | https://ubuntu.com/security/CVE-2026-33018 |
| URL | Tags |
|---|---|
| https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1 | Release Notes |
| https://github.com/saitoha/libsixel/security/advisories/GHSA-w46f-jr9f-rgvp | Exploit Vendor Advisory |