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CVE Vulnerability Details :
CVE-2026-39806
PUBLISHED
More InfoOfficial Page
Assigner-EEF
Assigner Org ID-6b3ad84c-e1a6-4bf7-a703-f496b71e49db
View Known Exploited Vulnerability (KEV) details
Published At-13 May, 2026 | 13:36
Updated At-13 May, 2026 | 18:27
Rejected At-
▼CVE Numbering Authority (CNA)
HTTP/1 chunked decoder infinite loop on requests with trailer fields in bandit

Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in mtrudel bandit allows unauthenticated remote denial of service via worker process exhaustion. 'Elixir.Bandit.HTTP1.Socket':do_read_chunked_data!/5 in lib/bandit/http1/socket.ex terminates only when the last-chunk line 0\r\n is followed immediately by the empty trailer line \r\n. RFC 9112 §7.1.2 permits zero or more trailer fields between them. When trailers are present, none of the match clauses fit: the catch-all arm computes a negative to_read, calls read_available!/2, receives <<>> on timeout, and tail-recurses with unchanged state. The worker process is pinned for the lifetime of the TCP connection. A handful of concurrent connections sending RFC-conformant chunked requests with trailer fields is sufficient to exhaust the Bandit worker pool and render the server unresponsive to all further traffic. No authentication, special headers, or large payload is required. Proxies such as NGINX and HAProxy legitimately forward trailer-bearing requests, so servers behind such proxies may be affected without any malicious client involvement. This issue affects bandit: from 1.6.1 before 1.11.1.

Affected Products
Vendor
mtrudel
Product
bandit
Collection URL
https://repo.hex.pm
Package Name
bandit
Repo
https://github.com/mtrudel/bandit
CPEs
  • cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*
Modules
  • 'Elixir.Bandit.HTTP1.Socket'
Program Files
  • lib/bandit/http1/socket.ex
Program Routines
  • 'Elixir.Bandit.HTTP1.Socket':do_read_chunked_data!/5
Default Status
unaffected
Versions
Affected
  • From 1.6.1 before 1.11.1 (semver)
Vendor
mtrudel
Product
bandit
Collection URL
https://github.com
Package Name
mtrudel/bandit
Repo
https://github.com/mtrudel/bandit
CPEs
  • cpe:2.3:a:mtrudel:bandit:*:*:*:*:*:*:*:*
Modules
  • 'Elixir.Bandit.HTTP1.Socket'
Program Files
  • lib/bandit/http1/socket.ex
Program Routines
  • 'Elixir.Bandit.HTTP1.Socket':do_read_chunked_data!/5
Default Status
unaffected
Versions
Affected
  • From e73e379ab59840e8561b5730878f16e29ab06217 before ae3520dfdbfab115c638f8c7f6f6b805db34e1ab (git)
Problem Types
TypeCWE IDDescription
CWECWE-835CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')
Type: CWE
CWE ID: CWE-835
Description: CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')
Metrics
VersionBase scoreBase severityVector
4.08.7HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Version: 4.0
Base score: 8.7
Base severity: HIGH
Vector:
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Metrics Other Info
Impacts
CAPEC IDDescription
CAPEC-469CAPEC-469 HTTP DoS
CAPEC ID: CAPEC-469
Description: CAPEC-469 HTTP DoS
Solutions

Configurations

Workarounds

Exploits

Credits

finder
Peter Ullrich
remediation developer
Mat Trudel
analyst
Jonatan Männchen
Timeline
EventDate
Replaced By

Rejected Reason

References
HyperlinkResource
https://github.com/mtrudel/bandit/security/advisories/GHSA-rf5q-vwxw-gmrf
vendor-advisory
related
https://cna.erlef.org/cves/CVE-2026-39806.html
related
https://osv.dev/vulnerability/EEF-CVE-2026-39806
related
https://github.com/mtrudel/bandit/commit/ae3520dfdbfab115c638f8c7f6f6b805db34e1ab
patch
Hyperlink: https://github.com/mtrudel/bandit/security/advisories/GHSA-rf5q-vwxw-gmrf
Resource:
vendor-advisory
related
Hyperlink: https://cna.erlef.org/cves/CVE-2026-39806.html
Resource:
related
Hyperlink: https://osv.dev/vulnerability/EEF-CVE-2026-39806
Resource:
related
Hyperlink: https://github.com/mtrudel/bandit/commit/ae3520dfdbfab115c638f8c7f6f6b805db34e1ab
Resource:
patch
▼Authorized Data Publishers (ADP)
CISA ADP Vulnrichment
Affected Products
Metrics
VersionBase scoreBase severityVector
Metrics Other Info
Impacts
CAPEC IDDescription
Solutions

Configurations

Workarounds

Exploits

Credits

Timeline
EventDate
Replaced By

Rejected Reason

References
HyperlinkResource
https://github.com/mtrudel/bandit/security/advisories/GHSA-rf5q-vwxw-gmrf
exploit
Hyperlink: https://github.com/mtrudel/bandit/security/advisories/GHSA-rf5q-vwxw-gmrf
Resource:
exploit
Details not found