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7.5

CVE-2026-32873: Gleam Web Server Crashes with Infinite Loop on Invalid Trailer Headers

CVE-2026-32873 · published 7 months ago
Summary

Gleam web server versions 0.8.0 through 3.0.4 can crash if an attacker sends a specially crafted request with invalid trailer headers. This can cause the server to run out of control and freeze. Upgrade to version 3.0.5 to fix the issue.

What to do
  • Update vshakitskiy ewe to version 3.0.5 or later.
Affected software
VendorProductAffected versions
vshakitskiy ewe >= 0.8.0, < 3.0.5
cpe:2.3:a:vshakitskiy:ewe:*:*:*:*:*:*:*:*
Original advisory text
ewe is a Gleam web server. Versions 0.8.0 through 3.0.4 contain a bug in the handle_trailers function where rejected trailer headers (forbidden or undeclared) cause an infinite loop. When handle_tr...
ewe is a Gleam web server. Versions 0.8.0 through 3.0.4 contain a bug in the handle_trailers function where rejected trailer headers (forbidden or undeclared) cause an infinite loop. When handle_trailers encounters such a trailer, three code paths (lines 520, 523, 526) recurse with the original buffer (rest) instead of advancing past the rejected header (Buffer(header_rest, 0)), causing decoder.decode_packet to re-parse the same header on every iteration. The resulting loop has no timeout or escape — the BEAM process permanently wedges at 100% CPU. Any application that calls ewe.read_body on chunked requests is affected, and this is exploitable by any unauthenticated remote client before control returns to application code, making an application-level workaround impossible. This issue is fixed in version 3.0.5.
Fix within
Internet-facing 14 days
Internal 60 days
  • Not known to be exploited
  • Can be exploited automatically
  • Gives an attacker partial control
Severity
7.5 High
Exploitation
<1% chance of attack within 30 days
Type
CWE-825Expired Pointer Dereference
CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')
Timeline
Published20 Mar 2026
Updated4 Nov 2026
First seen20 Mar 2026
Sources
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