Skip to content
Fencer Intel
medium 5.3

CVE-2026-34715 json

ewe Has Improper Neutralization of CRLF Sequences in HTTP Headers (HTTP Request/Response Splitting)

published 7mo ago modified 3mo ago also EUVD-2026-18468 , GHSA-x2w3-23jr-hrpf

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits
0
none known

Summary

ewe is a Gleam web server. Prior to version 3.0.6, the encode_headers function in src/ewe/internal/encoder.gleam directly interpolates response header keys and values into raw HTTP bytes without validating or stripping CRLF (\r\n) sequences. An application that passes user-controlled data into response headers (e.g., setting a Location redirect header from a request parameter) allows an attacker to inject arbitrary HTTP response content, leading to response splitting, cache poisoning, and possible cross-site scripting. Notably, ewe does validate CRLF in incoming request headers via validate_field_value() in the HTTP/1.1 parser — but provides no equivalent protection for outgoing response headers in the encoder. This issue has been patched in version 3.0.6.

Patch / fix

  • hex ewe 3.0.6
  • vshakitskiy ewe 3.0.6

Is CVE-2026-34715 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
7mo ago

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/vshakitskiy/ewe/security/advisories/GHSA-x2w3-23jr-hrpf referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
hex ewe
<3.0.6
3.0.6

Affected products

  • vshakitskiy ewe

Classification

Weakness
  • CWE-113 Improper Neutralization of CRLF Sequences in HTTP Headers

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.