CVE-2026-7790— Unbounded chunk-size hex digits in cowlib cause quadratic CPU and memory DoS

Unbounded chunk-size hex digits in cowlib cause quadratic CPU and memory DoS

Uncontrolled Resource Consumption vulnerability in ninenines cowlib (cow_http_te module) allows Excessive Allocation. The chunked transfer-encoding parser in cow_http_te accepts an unbounded number of hex digits in the chunk-size field. Each digit causes a bignum multiplication (Len * 16 + digit), so parsing N hex digits requires O(N²) CPU work and O(N) memory. Additionally, when input is drip-fed, the parser discards the accumulated length on each partial read and restarts from zero on resumption, raising the cost to O(N³). An unauthenticated remote attacker can exploit this by sending an HTTP/1.1 request with Transfer-Encoding: chunked and a very long chunk-size hex string to cause denial of service through CPU exhaustion and memory amplification. This vulnerability is associated with program file src/cow_http_te.erl and program routines cow_http_te:stream_chunked/2, cow_http_te:chunked_len/4. This issue affects cowlib: from 0.6.0 before 2.16.1.

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未加控制的资源消耗(资源穷尽)

Cowlib 资源管理错误漏洞

Cowlib是Nine Nines开源的一个Web协议消息解析与构建库。 cowlib 0.6.0版本至2.16.1之前版本存在资源管理错误漏洞，该漏洞源于cow_http_te模块中分块传输编码解析器接受无限制的十六进制数字，可能导致CPU耗尽和内存放大，导致拒绝服务。

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