CVE-2026-66731 (GCVE-0-2026-66731)
Vulnerability from cvelistv5 – Published: 2026-07-27 16:57 – Updated: 2026-07-31 18:20 X_Open Source
VLAI
EPSS
VEX
Title
facil.io 0.7.5 - 0.7.6 HTTP/1.1 Chunked Transfer Encoding Parser Crash DoS
Summary
facil.io 0.7.5 through 0.7.6 contains a denial-of-service vulnerability in the HTTP/1.1 chunked transfer encoding parser that allows unauthenticated remote attackers to crash the server by sending a negative chunk size value. Attackers can send a single POST request with a Transfer-Encoding: chunked header containing a leading minus sign in the chunk size field, causing the parser in http1_parser.h to compute a large positive integer from the negated value, corrupting internal state and moving the read pointer into unmapped memory resulting in a fault.
Severity
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-27 17:30 UTC
CWE
- CWE-125 - Out-of-bounds Read
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://tpaidakis.com/writeups/facilio-parser-dos/ | technical-descriptionexploit |
| https://github.com/theopaid/Negative-Chunk-Size-P… | technical-descriptionexploit |
| https://www.vulncheck.com/advisories/facil-io-htt… | third-party-advisory |
Impacted products
Date Public
2026-07-24 00:00
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