CVE detail
CVE-2026-43966
Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') vulnerability in ninenines cowlib allows HTTP response splitting via non-VCHAR bytes in structured-fields string values. cow_http_struct_hd:escape_string/2 in cowlib only escapes \ and ", passing all other bytes through verbatim. This creates an encoder/decoder asymmetry: the matching parser accepts only printable ASCII (0x20–0x7E, excluding " and \), but the encoder emits any byte including CR and LF. An application that builds a structured HTTP header via cow_http_struct_hd:item/1 (or a higher-level wrapper such as cow_http_hd:wt_protocol/1) from attacker-controlled input can have \r\n injected into the serialized header value. Once on the wire, the injected CRLF terminates the current header and any following bytes are interpreted as a new header, enabling HTTP response splitting. This issue affects cowlib from 2.9.0.
Buzz score
Why this CVE is surfacing
This all-time snapshot uses the same composite formula as Trending across a 30-year evidence window, rather than a current rolling window.
Buzz score components · mention 17.9 · diversity 16.5 · KEV 0.0 · OTX 0.0 · PoC 0.0
Why it matters now
Mention timeline
- Total mentions
- 0
- within the 30d window
- Peak daily
- 0
- highest bucket
Evidence
Source links by recency
5 source links · newest first
- CVE-2026-43966 HTTP Response Splitting via Non-VCHAR Bytes in cow_http_struct_hd:escape_string/2Microsoft MSRC
Information published.
vendormsrc.microsoft.comJun 19, 2026, 8:01 AM No excerpt available.
Exploitosv.devJun 8, 2026, 5:16 PMNo excerpt available.
Exploitgithub.comJun 8, 2026, 5:16 PMNo excerpt available.
Exploitgithub.comJun 8, 2026, 5:16 PM- https://cna.erlef.org/cves/CVE-2026-43966.htmlcna.erlef.org
No excerpt available.
Vendor Advisorycna.erlef.orgJun 8, 2026, 5:16 PM
Exploit code
Public exploit repository references
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0 repository references · best confidence N/A · max 0 stars
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