CVE-2026-7790: ninenines cowlib · Uncontrolled Resource Consumption
Affects ninenines cowlibSource CVE Database V5
Not known to be exploited · CVSS 8.7 High : upgrade to 2.16.1 soon.
Data as of 30 Oct 2026, 06:59 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 37% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 2.16.1, a4b8039ce8c93ab00867ef6b7e888822c09f4369
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 11 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade cowlib to 2.16.1; cowlib to a4b8039ce8c93ab00867ef6b7e888822c09f4369.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| nineninescowlib | Affected
| Fixed in
|
| nineninescowlib | Affected
| Fixed in
|
GitHubninenines/cowlibpkg:github/ninenines/cowlibOther threats | Affected
| Fixed in– |
Hexcowlibpkg:hex/cowlibOther threats | Affected
| Fixed in
|
CPE configurations (1)
cpe:2.3:a:ninenines:cowlib:*:*:*:*:*:*:*:*
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, consider implementing network-level protections such as limiting the size and rate of chunked transfer-encoding requests or using a web application firewall to detect and block suspiciously long chunk-size headers. Monitor for unusual resource usage patterns that may indicate exploitation attempts.
Description
CVE-2026-7790 is a high-severity vulnerability in the ninenines cowlib library, specifically in the cow_http_te module's chunked transfer-encoding parser. The parser accepts an unbounded number of hexadecimal digits in the chunk-size field, leading to excessive CPU and memory consumption. An unauthenticated remote attacker can exploit this by sending a specially crafted HTTP/1.1 request with a very long chunk-size hex string, causing denial of service through resource exhaustion. This affects cowlib versions from 0.6.0 before 2.16.1.