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CVE-2025-20260 is an out-of-bounds write vulnerability in the ClamAV PDF file parser. Incorrect allocation of memory buffers during PDF processing can permit a crafted PDF to cause a buffer overflow. Although the underlying flaw predates ClamAV 1.0.0, it became triggerable after version 1.0.0 enabled larger allocations based on untrusted input. The issue affects supported ClamAV versions when configured with sufficiently large scan limits.
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2 valid exploits after Mallory filtered fakes, detection scripts, and README-only repos.
Small two-file proof-of-concept repository for CVE-2025-20260 targeting ClamAV PDF scanning. The README describes a buffer overflow in ClamAV's handling of malicious PDFs and states the impact may include denial of service or arbitrary code execution. The only code file, clamshank.py, is a standalone Python generator that writes a malformed PDF named clam-cve.pdf. The PDF template sets an abnormally large /Length value (1073741824) plus extra numeric junk ('444444444444') and uses /Filter /ASCII85Decode. The script then appends a very large repeated ASCII85 sequence ('hS?8M') in a loop from 0 to 1073741825 stepping by 5, creating an oversized encoded stream before closing the PDF structure. There are no network callbacks, exploit delivery routines, shell payloads, or post-exploitation features; this is purely a file-generation PoC intended to be supplied to a vulnerable ClamAV scanner by some external mechanism. Repository structure is minimal: README.md for vulnerability description and clamshank.py as the sole exploit artifact.
This repository contains a proof-of-concept exploit for CVE-2025-20260, a critical vulnerability in ClamAV's PDF parsing logic. The main file, 'clamshank.py', is a Python script that generates a malicious PDF file ('clam-cve.pdf'). The script constructs a PDF with a manipulated /Length field and an extremely large ASCII85-encoded stream, designed to trigger the vulnerability in ClamAV when the file is scanned or processed. The repository also includes a README and a LICENSE file. There are no network endpoints or remote attack vectors; the exploit is file-based and targets local or server-side PDF scanning by ClamAV. The exploit is a proof-of-concept and does not include a remote payload or post-exploitation functionality.
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15 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A buffer overflow vulnerability in squidclamav's ClamAV PDF scanning functionality, referenced for EPEL 9.
A buffer overflow vulnerability in ClamAV PDF scanning as referenced for squidclamav on EPEL 8.
A critical vulnerability in ClamAV listed as a trending CVE for the week. Specifics not detailed in the content.
A buffer overflow write vulnerability in the ClamAV PDF file parser that can cause denial of service or potentially enable remote code execution under specific large scan-limit configurations.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.