CVE-2026-44636— libsixel: integer overflow in encoder
Possible ATT&CK Techniques 1AI
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I. Basic Information for CVE-2026-44636
Vulnerability Information
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Vulnerability Title
libsixel: integer overflow in encoder
Source: NVD (National Vulnerability Database)
Vulnerability Description
libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From to 1.8.7-r1, signed integer overflow in sixel_encode_highcolor's allocation size calculation can lead to a heap buffer overflow. The public sixel_encode entry point validates only that width and height are greater than zero, with no upper bound. width and height are multiplied as plain int when computing the allocation size for paletted_pixels and normalized_pixels. Any caller that asks libsixel to encode a pixel buffer with width times height greater than INT_MAX (about 2.15 billion) will hit a wrapped allocation size; under the right wrap, the malloc succeeds with a buffer much smaller than the encoder expects, and the encoder writes past the end of the heap allocation. This vulnerability is fixed in 1.8.7-r2.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: NVD (National Vulnerability Database)
Vulnerability Type
堆缓冲区溢出
Source: NVD (National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-44636
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- https://github.com/saitoha/libsixel/security/advisories/GHSA-hx93-w8p2-ffh5x_refsource_CONFIRM
- https://nvd.nist.gov/vuln/detail/CVE-2026-44636
Same Patch Batch · saitoha · 2026-05-14 · 3 CVEs total
| CVE-2026-44637 | 7.1 HIGH | libsixel: integer overflow in parser |
| CVE-2026-44638 | 2.5 LOW | libsixel: NULL pointer dereference |
IV. Related Vulnerabilities
Same product: libsixel
- CVE-2026-44637
libsixel: integer overflow in parser - CVE-2026-44638
libsixel: NULL pointer dereference - CVE-2026-33023
libsixel: Use-after-free in load_with_gdkpixbuf() - CVE-2026-33021
libsixel: Use-after-free in sixel_encoder_encode_bytes() - CVE-2026-33020
libsixel: Integer Overflow in write_png_to_file() leads to H
Same vendor: saitoha
- CVE-2026-44637
libsixel: integer overflow in parser - CVE-2026-44638
libsixel: NULL pointer dereference - CVE-2026-33023
libsixel: Use-after-free in load_with_gdkpixbuf() - CVE-2026-33021
libsixel: Use-after-free in sixel_encoder_encode_bytes() - CVE-2026-33020
libsixel: Integer Overflow in write_png_to_file() leads to H
V. Comments for CVE-2026-44636
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