Vulnerability Details CVE-2026-7790
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 29.7%
CVSS Severity
CVSS v3 Score 7.5
Products affected by CVE-2026-7790
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cpe:2.3:a:ninenines:cowlib:0.6.0
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cpe:2.3:a:ninenines:cowlib:0.6.1
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cpe:2.3:a:ninenines:cowlib:0.6.2
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cpe:2.3:a:ninenines:cowlib:1.0.0
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cpe:2.3:a:ninenines:cowlib:1.0.1
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cpe:2.3:a:ninenines:cowlib:1.0.2
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cpe:2.3:a:ninenines:cowlib:1.1.0
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cpe:2.3:a:ninenines:cowlib:1.2.0
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cpe:2.3:a:ninenines:cowlib:1.3.0
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cpe:2.3:a:ninenines:cowlib:2.0.0
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cpe:2.3:a:ninenines:cowlib:2.0.1
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cpe:2.3:a:ninenines:cowlib:2.1.0
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cpe:2.3:a:ninenines:cowlib:2.10.0
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cpe:2.3:a:ninenines:cowlib:2.10.1
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cpe:2.3:a:ninenines:cowlib:2.11.0
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cpe:2.3:a:ninenines:cowlib:2.12.0
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cpe:2.3:a:ninenines:cowlib:2.12.1
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cpe:2.3:a:ninenines:cowlib:2.13.0
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cpe:2.3:a:ninenines:cowlib:2.14.0
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cpe:2.3:a:ninenines:cowlib:2.15.0
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cpe:2.3:a:ninenines:cowlib:2.16.0
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cpe:2.3:a:ninenines:cowlib:2.2.0
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cpe:2.3:a:ninenines:cowlib:2.2.1
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cpe:2.3:a:ninenines:cowlib:2.3.0
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cpe:2.3:a:ninenines:cowlib:2.4.0
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cpe:2.3:a:ninenines:cowlib:2.5.0
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cpe:2.3:a:ninenines:cowlib:2.5.1
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cpe:2.3:a:ninenines:cowlib:2.6.0
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cpe:2.3:a:ninenines:cowlib:2.7.0
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cpe:2.3:a:ninenines:cowlib:2.7.1
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cpe:2.3:a:ninenines:cowlib:2.7.2
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cpe:2.3:a:ninenines:cowlib:2.7.3
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cpe:2.3:a:ninenines:cowlib:2.8.0
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cpe:2.3:a:ninenines:cowlib:2.9.0
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cpe:2.3:a:ninenines:cowlib:2.9.1