What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 8.2 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-14 · updated 2026-10-26
• Weakness: CWE-770

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.

Affected products

• elixir-plug plug: from 1.4.0 before 1.15.4; from 1.16.0 before 1.16.3; from 1.17.0 before 1.17.1; from 1.18.0 before 1.18.2; from 1.19.0 before 1.19.2 — fixed in 1.15.4, 1.16.3, 1.17.1, 1.18.2, 1.19.2

How to fix

Upgrade to a fixed version: elixir-plug plug 1.15.4, 1.16.3, 1.17.1, 1.18.2. Check the vendor advisory for mitigations.

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

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