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VulnerabilityPublished Updated

CVE-2026-7790: ninenines cowlib · Uncontrolled Resource Consumption

Affects ninenines cowlibSource CVE Database V5

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Not known to be exploited · CVSS 8.7 High : upgrade to 2.16.1 soon.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 4.0 base score
8.7High
How severe the flaw is on the 0–10 CVSS scale.
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 11 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
nineninescowlibAffected
  • >=0.6.0 <2.16.1
Fixed in
  • 2.16.1
nineninescowlibAffected
  • ≥ 8c0e428b012c59f553a264f285ed89d36f791e3e, < a4b8039ce8c93ab00867ef6b7e888822c09f4369
Fixed in
  • a4b8039ce8c93ab00867ef6b7e888822c09f4369
GitHubninenines/cowlibpkg:github/ninenines/cowlibOther threatsAffected
  • =0.6.0
Fixed in–
Hexcowlibpkg:hex/cowlibOther threatsAffected
  • >=0.6.0 <2.16.1
Fixed in
  • 2.16.1

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.

References

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