cow_http_struct_hd:escape_string/2 · HTTP Response Splitting via Non-VCHAR Bytes
Affects MicrosoftSource GCVE Database
Not known to be exploited · CVSS 6.3 Medium : upgrade to 4401b858f2229abb3ea115c60924f6c77e5f8aa3 when convenient.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 4401b858f2229abb3ea115c60924f6c77e5f8aa3
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 8 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 2026.
What to do
Upgrade cowlib to 4401b858f2229abb3ea115c60924f6c77e5f8aa3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| nineninescowlib | Affected
| Fixed in– |
| nineninescowlib | Affected
| Fixed in
|
Hexcowlibpkg:hex/cowlibOther threats | Affected
| Fixed in– |
Hexcowlibpkg:hex/cowlibOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle