CVE-2026-8468 - Vulnerability Details

- Unbounded buffer accumulation in multipart header parsing causes denial of service in plug

Description

Allocation of Resources Without Limits or Throttling vulnerability in plug_project plug allows denial of service via unbounded buffer accumulation in multipart header parsing.

'Elixir.Plug.Conn':read_part_headers/2 in lib/plug/conn.ex does not obey its :length parameter. There is no upper bound on the size of the accumulated buffer. By contrast, the sibling function read_part_body has an explicit byte_size(acc) > length guard that stops accumulation once a limit is reached. No such guard exists in read_part_headers. An unauthenticated remote attacker can exhaust server memory by sending a crafted multipart/form-data request, causing a denial of service.

This issue affects plug from 1.4.0 before 1.15.4, 1.16.3, 1.17.1, 1.18.2, and 1.19.2.

Published: 2026-05-14

Score: 8.2 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

Elixir.Plug.Conn.read_part_headers/2 ignores its :length parameter, allowing unbounded accumulation of multipart headers. Because no size limit is enforced, a crafted multipart/form-data request can fill the BEAM memory of the handling process until it crashes, resulting in denial of service. This is a classic case of Unbounded Resource Consumption (CWE‑770).

Affected Systems

The vulnerability is present in plug versions from 1.4.0 through 1.15.4, as well as 1.16.3, 1.17.1, 1.18.2, and 1.19.2. The affected software is the plug library (elixir‑plug:plug) used in Elixir applications.

Risk and Exploitability

The CVSS score of 8.2 indicates a high severity of impact. Although the EPSS score is not available, the ecological lack of exploitation data does not diminish the potential threat; an unauthenticated attacker can trigger the effect simply by sending a crafted multipart request. The CVE is not listed in the CISA KEV catalog, but the attack requires only network connectivity and imposes no authentication or privilege prerequisites.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

elixir-plug

plug

unaffected

Version	Status	Constraints
`1.4.0`	affected	< 1.15.4
`1.16.0`	affected	< 1.16.3
`1.17.0`	affected	< 1.17.1
`1.18.0`	affected	< 1.18.2
`1.19.0`	affected	< 1.19.2

elixir-plug

plug

unaffected

Version	Status	Constraints
`c52b2f32c90bccd718202bafccb5f95594e30183`	affected	< *

No data.

Vendor Product Confidence Versions

Elixir-plug

Plug Cowboy

82%

Version	Status	Scheme	Platform
`[1.4.0,1.15.4)`	affected	semver	—
`[1.16.0,1.16.3)`	affected	semver	—
`[1.17.0,1.17.1)`	affected	semver	—
`[1.18.0,1.18.2)`	affected	semver	—
`[1.19.0,1.19.2)`	affected	semver	—

Elixir-plug

Plug Cowboy

82%

Version	Status	Scheme	Platform
`c52b2f32c90bccd718202bafccb5f95594e30183`	affected	code_commit	—

Plug Project

Plug

—

Version	Status	Scheme	Platform
`[1.4.0,1.15.4)`	affected	semver	—
`[1.16.0,1.16.3)`	affected	semver	—
`[1.17.0,1.17.1)`	affected	semver	—
`[1.18.0,1.18.2)`	affected	semver	—
`[1.19.0,1.19.2)`	affected	semver	—

Plug Project

Plug

—

Version	Status	Scheme	Platform
`c52b2f32c90bccd718202bafccb5f95594e30183`	affected	code_commit	—

Found an issue or want to improve our Enrichment? You can suggest it directly by opening an issue on our dedicated GitHub repository .

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

Upgrade plug to the latest released version (e.g., 1.20.0 or newer) from Hex.
Configure BEAM memory limits (e.g., vm_procs, max_heap_size) to constrain the amount of RAM a process can consume during multipart parsing.
Limit concurrent multipart uploads at the application or reverse‑proxy level to reduce the number of processes that can accumulate memory at the same time.

Generated by OpenCVE AI on May 14, 2026 at 12:21 UTC.

Tracking

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Advisories

Source	ID	Title
Github GHSA	GHSA-468c-vq7p-gh64	Plug: Unbounded buffer accumulation in multipart header parsing causes denial of service

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00269.

Exploitation none

Automatable no

Technical Impact partial

References

Link	Providers
https://cna.erlef.org/cves/CVE-2026-8466.html
https://cna.erlef.org/cves/CVE-2026-8468.html
https://github.com/elixir-plug/plug/commit/2cb7958d33030aa826b0c7404375844d4593d43a
https://github.com/elixir-plug/plug/commit/33858427c7f2737d560a2e40a0c9a9270d77d1d7
https://github.com/elixir-plug/plug/commit/aa69c5ece99c40ded88b8c6581ecc86664b0b734
https://github.com/elixir-plug/plug/commit/d5dfffe25e975585227b1b85d247b0d14164bc45
https://github.com/elixir-plug/plug/commit/df812a1527bae9e941965e897308a2b8bbf83a94
https://github.com/elixir-plug/plug/security/advisories/GHSA-468c-vq7p-gh64
https://osv.dev/vulnerability/EEF-CVE-2026-8468

History

Thu, 14 May 2026 18:30:00 +0000

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Thu, 14 May 2026 15:00:00 +0000

Type	Values Removed	Values Added
First Time appeared		Elixir-plug Elixir-plug plug Cowboy
Vendors & Products		Elixir-plug Elixir-plug plug Cowboy

Thu, 14 May 2026 11:30:00 +0000

Type	Values Removed	Values Added
Description	Allocation of Resources Without Limits or Throttling vulnerability in plug_project plug allows denial of service via unbounded buffer accumulation in multipart header parsing. plug_multipart in src/plug_multipart.erl is a fork of the cow_multipart module from ninenines cowboy (CVE-2026-8466). The same unbounded accumulation pattern is present in 'Elixir.Plug.Conn':read_part_headers/2 in lib/plug/conn.ex: it accumulates incoming request bytes into a growing binary with no upper-bound check. When plug_multipart:parse_headers/2 returns more or {more, Buffer}, the function reads up to 64 KB from the underlying socket and recurses with the enlarged buffer. There is no equivalent of the byte_size(acc) > length guard present in the sibling function read_part_body/8. An unauthenticated attacker can send a multipart/form-data request whose body never yields a complete header section — for example, a body that never contains the advertised boundary delimiter, or one whose header lines never contain \r\n\r\n — and force the server process to accumulate memory linearly with the bytes the protocol layer is willing to deliver. A handful of concurrent such uploads is sufficient to exhaust BEAM memory. This issue affects plug from 1.4.0 before 1.15.4, 1.16.3, 1.17.1, 1.18.2, and 1.19.2.	Allocation of Resources Without Limits or Throttling vulnerability in plug_project plug allows denial of service via unbounded buffer accumulation in multipart header parsing. 'Elixir.Plug.Conn':read_part_headers/2 in lib/plug/conn.ex does not obey its :length parameter. There is no upper bound on the size of the accumulated buffer. By contrast, the sibling function read_part_body has an explicit byte_size(acc) > length guard that stops accumulation once a limit is reached. No such guard exists in read_part_headers. An unauthenticated remote attacker can exhaust server memory by sending a crafted multipart/form-data request, causing a denial of service. This issue affects plug from 1.4.0 before 1.15.4, 1.16.3, 1.17.1, 1.18.2, and 1.19.2.

Thu, 14 May 2026 10:45:00 +0000

Type	Values Removed	Values Added
Description		Allocation of Resources Without Limits or Throttling vulnerability in plug_project plug allows denial of service via unbounded buffer accumulation in multipart header parsing. plug_multipart in src/plug_multipart.erl is a fork of the cow_multipart module from ninenines cowboy (CVE-2026-8466). The same unbounded accumulation pattern is present in 'Elixir.Plug.Conn':read_part_headers/2 in lib/plug/conn.ex: it accumulates incoming request bytes into a growing binary with no upper-bound check. When plug_multipart:parse_headers/2 returns more or {more, Buffer}, the function reads up to 64 KB from the underlying socket and recurses with the enlarged buffer. There is no equivalent of the byte_size(acc) > length guard present in the sibling function read_part_body/8. An unauthenticated attacker can send a multipart/form-data request whose body never yields a complete header section — for example, a body that never contains the advertised boundary delimiter, or one whose header lines never contain \r\n\r\n — and force the server process to accumulate memory linearly with the bytes the protocol layer is willing to deliver. A handful of concurrent such uploads is sufficient to exhaust BEAM memory. This issue affects plug from 1.4.0 before 1.15.4, 1.16.3, 1.17.1, 1.18.2, and 1.19.2.
Title		Unbounded buffer accumulation in multipart header parsing causes denial of service in plug
First Time appeared		Plug Project Plug Project plug
Weaknesses		CWE-770
CPEs		cpe:2.3:a:plug_project:plug::::::::
Vendors & Products		Plug Project Plug Project plug
References		https://cna.erlef.org/cves/CVE-2026-8466.html https://cna.erlef.org/cves/CVE-2026-8468.html https://github.com/elixir-plug/plug/commit/2cb7958d33030aa826b0c7404375844d4593d43a https://github.com/elixir-plug/plug/commit/33858427c7f2737d560a2e40a0c9a9270d77d1d7 https://github.com/elixir-plug/plug/commit/aa69c5ece99c40ded88b8c6581ecc86664b0b734 https://github.com/elixir-plug/plug/commit/d5dfffe25e975585227b1b85d247b0d14164bc45 https://github.com/elixir-plug/plug/commit/df812a1527bae9e941965e897308a2b8bbf83a94 https://github.com/elixir-plug/plug/security/advisories/GHSA-468c-vq7p-gh64 https://osv.dev/vulnerability/EEF-CVE-2026-8468
Metrics		cvssV4_0 `{'score': 8.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}`

Subscriptions

Elixir-plug Plug Cowboy

Plug Project Plug

MITRE

Status: PUBLISHED

Assigner: EEF

Published: 2026-05-14T10:29:51.062Z

Updated: 2026-05-27T15:41:29.241Z

Reserved: 2026-05-13T11:44:42.164Z

Link: CVE-2026-8468

Vulnrichment

Updated: 2026-05-14T17:54:03.803Z

NVD

Status : Deferred

Published: 2026-05-14T11:16:18.900

Modified: 2026-05-14T17:07:07.030

Link: CVE-2026-8468

Redhat

No data.

OpenCVE Enrichment

Updated: 2026-05-14T14:32:47Z

Weaknesses

CWE-770

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements Present

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Exploitation none

Automatable no

Technical Impact partial

Subscriptions

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