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VulnerabilityPublished Updated

CVE-2026-48743: envoyproxy envoy · HTTP Request/Response Smuggling

Affects envoyproxy envoySource CVE Database V5

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Not known to be exploited · CVSS 7.5 High · fixed in 1.38.1 : patch envoyproxy envoy soon.

Data as of 7 Nov 2026, 23:24 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 22% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.38.1, 1.37.3, 1.36.7 +1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 26 Jun 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 7 Nov 2026.

What to do

Upgrade envoy and envoyproxy/envoy to 1.38.1, 1.37.3, 1.36.7 or 1.35.11.

Affected software

ProductAffectedFixed in
envoyproxyenvoyAffected
  • >=1.38.0 <1.38.1
Fixed in
  • 1.38.1
envoyproxyenvoyAffected
  • >=1.37.0 <1.37.3
Fixed in
  • 1.37.3
envoyproxyenvoyAffected
  • >=1.36.0 <1.36.7
Fixed in
  • 1.36.7
envoyproxyenvoyAffected
  • >=1.35.0 <1.35.11
Fixed in
  • 1.35.11
GitHubenvoyproxy/envoypkg:github/envoyproxy/envoyOther threatsAffected
  • <1.35.11
  • <1.36.7
  • <1.37.3
  • <1.38.1
Fixed in
  • 1.35.11
  • 1.36.7
  • 1.37.3
  • 1.38.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

This vulnerability is fixed in Envoy versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1. Users should upgrade to these or later versions to remediate the issue. Patch status is confirmed by the version-based fixes; no other mitigation guidance is provided.

Description

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, Envoy can translate a downstream HTTP/3 request that is complete at the transport layer (HEADERS with FIN / headers-only close) but still carries a nonzero Content-Length into a complete upstream HTTP/1 request with unresolved body debt. In an HTTP/1 upstream deployment where the origin replies before reading the declared body and keeps the connection reusable, the beginning of the next Envoy-generated upstream request can be consumed as the first request's body. The remaining bytes are then parsed by the origin as a new HTTP/1 request. This was reproduced as a route-bypass/desync: direct /pwn was denied by Envoy, but the second downstream H3 stream received the response for backend-parsed GET /pwn HTTP/1.1. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.

References

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