CVE-2026-7790
Description
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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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
cowlibHex | >= 0.6.0, < 2.16.1 | 2.16.1 |
Affected products
2Patches
Vulnerability mechanics
References
6- github.com/ninenines/cowlib/commit/a4b8039ce8c93ab00867ef6b7e888822c09f4369nvdPatchWEB
- cna.erlef.org/cves/CVE-2026-7790.htmlnvdThird Party AdvisoryWEB
- github.com/advisories/GHSA-32p9-57cr-4x65ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-7790ghsaADVISORY
- osv.dev/vulnerability/EEF-CVE-2026-7790nvdThird Party AdvisoryWEB
- github.com/ninenines/cowlib/releases/tag/2.16.1ghsaWEB
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