Description
imagecodecs 2026.3.6 through 2026.10.10 contains an infinite loop vulnerability in ccitt_fax4_decode_size() that allows attackers to hang the calling process by supplying a crafted CCITT Group 4 stream. Attackers can provide an 8-byte G4 stream lacking EOFB to ccittfax4_decode() or the numcodecs Ccittfax4 codec, consuming full CPU until the process is killed.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| cgohlke | imagecodecs | 2026.3.6 – ≤ 2026.10.10 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-imagecodecs | 2026.10.10-2.1 | openSUSE-SU-2026:12406-1 |
Advisories 1
- openSUSE-SU-2026:12406-1 python313-imagecodecs-2026.10.10-2.1 on GA media SUSE / openSUSE Security Updates · Nov 4, 2026
References
- GitHub Issue #158 issue-tracking
- https://github.com/cgohlke/imagecodecs/blob/v2026.10.10/3rdparty/ccitt/ccitt.c#L1449 technical-description
- https://github.com/cgohlke/imagecodecs product
- VulnCheck Advisory: imagecodecs 2026.3.6 through 2026.10.10 Infinite Loop via ccittfax4_decode() third-party-advisory