CVE-2026-7790
HIGH7.5EPSS 0.11%cowlib cow_http_te module: Uncontrolled Resource Consumption vulnerability allows Excessive Allocation
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.
Affected packages (2)
- Debian/erlang-cowlibfrom 0
- Hex/cowlib>= 0.6.0, < 2.16.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
References (7)
- ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-7790
- ADVISORYhttps://security-tracker.debian.org/tracker/CVE-2026-7790
- PATCHhttps://github.com/ninenines/cowlib
- WEBhttps://cna.erlef.org/cves/CVE-2026-7790.html
- WEBhttps://github.com/ninenines/cowlib/commit/a4b8039ce8c93ab00867ef6b7e888822c09f4369
- WEBhttps://github.com/ninenines/cowlib/releases/tag/2.16.1
- WEBhttps://osv.dev/vulnerability/EEF-CVE-2026-7790