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CVE-2026-120251— imagecodecs 2026.3.6 through 2026.10.10 Infinite Loop via ccittfax4_decode()

Quick assessment

Affected
cgohlke imagecodecs
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

imagecodecs 2026.3.6 至 2026.10.10 版本中的 函数存在无限循环漏洞。攻击者可通过提供精心构造的 CCITT Group 4 数据流，使调用该函数的进程陷入挂起状态。具体而言，攻击者可向 函数或 numcodecs 库中的 编解码器提交一个缺少 EOFB（End of Block）标记的 8 字节 G4 数据流，导致 CPU 占用率达到 100%，直至进程被强制终止。

CVSS 5.5 · Medium EPSS 0.12% · P2

Possible ATT&CK Techniques 1 AI

T1499.003 · Application Exhaustion Flood

Affected Version Matrix 1

VendorProduct Version RangeStatus
cgohlke imagecodecs 2026.3.6≤ 2026.10.10 affected
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I. Basic Information for CVE-2026-120251

Vulnerability Information
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Vulnerability Title
imagecodecs 2026.3.6 through 2026.10.10 Infinite Loop via ccittfax4_decode()
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
不可达退出条件的循环(无限循环)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
cgohlke imagecodecs 2026.3.6 ~ 2026.10.10 -

II. Public POCs for CVE-2026-120251

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-120251

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Other References for CVE-2026-120251 (4)

IV. Related Vulnerabilities

Same product: imagecodecs
Same vendor: cgohlke
Same weakness: CWE-835