# CVE-2026-69664: httpd parks a request worker indefinitely on a malformed chunk size sent after the headers

Status: published. Published: 2026-09-01. Updated: 2026-11-11.

Missing Release of Resource after Effective Lifetime vulnerability in Erlang/OTP inets httpd allows an unauthenticated remote attacker to cause denial of service by sending a request with a chunked body whose chunk-size line is not a hexadecimal number. The worker serving the connection is never released and no timeout reclaims it, so repeating the request across connections occupies every available worker and denies service to legitimate clients. No authentication is required and the default configuration is affected.

The chunk-size line must arrive in a write separate from the headers. When the body accompanies the headers, httpd_request_handler:handle_body/3 calls http_chunk:decode/3 inside a try ... catch throw:Error, so the {error, {chunk_size, _}} thrown by http_chunk:decode_size/4 is answered with 400 Bad Request. When the chunk size arrives later, the decoder is resumed through a bare catch in httpd_request_handler:handle_info/2, which converts the throw into a return value rather than raising it; the resulting error tuple is then treated as the next decoder continuation, the socket is re-armed, and the worker waits for data that never comes. The request timeout has already been cancelled at the point the headers were accepted, and the periodic byte-rate check is only armed when minimum_bytes_per_second is configured, which it is not by default.

This issue affects OTP from OTP 18.1.4 before OTP 27.3.4.17, OTP 28.5.0.6, and OTP 29.0.6, corresponding to inets from 6.0.3 before 9.3.2.7, 9.6.2.3, and 9.7.2.

## Remediation

- workaround: * Set minimum_bytes_per_second in the httpd configuration, for example {minimum_bytes_per_second, 200}. This arms a periodic byte-rate check that terminates a connection which has stopped delivering data, reclaiming the parked worker within a few seconds. The check is disabled by default, and any positive value suffices because an affected connection delivers no further data at all.
* Place a reverse proxy in front of httpd that validates chunked transfer encoding and rejects malformed chunk framing before it reaches httpd.
* Restrict access to the server to trusted clients where the deployment allows it. (source: CNA: EEF)
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: EEF) — https://github.com/erlang/otp/commit/a3adf63078438c86527d704e23282b7721d8ca12
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: EEF) — https://github.com/erlang/otp/commit/df1a9ca4666e2fdfc44886bfaae76de086d803f6
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: EEF) — https://github.com/erlang/otp/commit/bd4e74348c6be8a49f060da6fd48d43f3a960292

## Affected products and versions

- Erlang / OTP (otp): ≥ 18.1.4; < * (affected, otp); unaffected at 27.3.4.17; unaffected at 28.5.0.6; unaffected at 29.0.6. Source: CNA: EEF
- Erlang / OTP (inets): ≥ 6.0.3; < * (affected, otp); unaffected at 9.3.2.7; unaffected at 9.6.2.3; unaffected at 9.7.2. Source: CNA: EEF
- Erlang / OTP (erlang/otp): ≥ 77acb473d8f056f6f534395f131c6e45693797f0; < * (affected, git); unaffected at a3adf63078438c86527d704e23282b7721d8ca12; unaffected at df1a9ca4666e2fdfc44886bfaae76de086d803f6; unaffected at bd4e74348c6be8a49f060da6fd48d43f3a960292. Source: CNA: EEF

## Severity and prioritization

- CVSS 4.0: 8.7 (high); 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; source: CNA: EEF

- CISA KEV: No listing in collected sources

- EPSS: 0.95% as of 2026-11-10; percentile 61.52%

- SSVC: exploitation poc; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-772

## Exploit evidence

- exploit: https://github.com/erlang/otp/security/advisories/GHSA-mr35-8h7w-w3gq (ADP: CISA-ADP)

## References

- https://github.com/erlang/otp/security/advisories/GHSA-mr35-8h7w-w3gq (CNA: EEF; related, vendor-advisory)

- https://cna.erlef.org/cves/CVE-2026-69664.html (CNA: EEF; related)

- https://osv.dev/vulnerability/EEF-CVE-2026-69664 (CNA: EEF; related)

- https://www.erlang.org/doc/system/versions.html#order-of-versions (CNA: EEF; x_version-scheme)

- https://github.com/erlang/otp/commit/77acb473d8f056f6f534395f131c6e45693797f0 (CNA: EEF; related)

- https://github.com/erlang/otp/commit/a3adf63078438c86527d704e23282b7721d8ca12 (CNA: EEF; patch)

- https://github.com/erlang/otp/commit/df1a9ca4666e2fdfc44886bfaae76de086d803f6 (CNA: EEF; patch)

- https://github.com/erlang/otp/commit/bd4e74348c6be8a49f060da6fd48d43f3a960292 (CNA: EEF; patch)

- https://github.com/erlang/otp/security/advisories/GHSA-mr35-8h7w-w3gq (ADP: CISA-ADP; exploit)

## Provenance

- CNA: EEF: https://www.cve.org/CVERecord?id=CVE-2026-69664; retrieved 2026-11-11; source updated 2026-11-11

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-69664; retrieved 2026-11-11; source updated Not reported

Revision: e2e81146aa2e71a4a8663a2db31be352a80b6d6f036871c9bd29d5f403af2ac7

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