httpd parks a request worker indefinitely on a malformed chunk size sent after the headers
Erlang · OTP
8.7HighCVSS 4.0
Recommended action
Within 7 days
High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.
Patch available
Distribution package intelligence
Ubuntu vendor package status
Canonical’s release and source-package findings are shown separately from local repository availability.
1 package state
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
Ubuntu release
Source package
Vendor state
Fixed version
Evidence
Ubuntu 24.04 LTSnoble · standard archive
erlang
Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
1 current
CVE-2026-69664 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityotp: inets: Erlang/OTP inets httpd: Denial of Service via malformed chunked HTTP request
41 known affected
The vendor explicitly identifies these products as affected by this CVE.
erlang-asn1 as a component of Red Hat OpenStack Platform 16.2
erlang-compiler as a component of Red Hat OpenStack Platform 16.2
erlang-crypto as a component of Red Hat OpenStack Platform 16.2
erlang-eldap as a component of Red Hat OpenStack Platform 16.2
erlang-erts as a component of Red Hat OpenStack Platform 16.2
erlang-hipe as a component of Red Hat OpenStack Platform 16.2
erlang-inets as a component of Red Hat OpenStack Platform 16.2
erlang-kernel as a component of Red Hat OpenStack Platform 16.2
erlang-mnesia as a component of Red Hat OpenStack Platform 16.2
erlang-os_mon as a component of Red Hat OpenStack Platform 16.2
erlang-parsetools as a component of Red Hat OpenStack Platform 16.2
erlang-public_key as a component of Red Hat OpenStack Platform 16.2
Summary
A flaw was found in Erlang/OTP inets httpd. An unauthenticated remote attacker can exploit this vulnerability by sending a malformed chunked HTTP request. Specifically, if the chunk-size line is not a hexadecimal number and arrives separately from the headers, the server worker handling the request will not be released. Repeated exploitation can exhaust all available workers, leading to a denial of service (DoS) for legitimate clients.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Optional official sources
National CERT insights ?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.
Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.
Official European source
ENISA European Vulnerability Database
Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.
1 current
ENISA EUVD identifier
EUVD-2026-69381
No EUVD known-exploited evidence
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, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 6.0.3 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2.
EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
8.7 · CVSS 4.0
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days
High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.
Patch available
01
What, why and how
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, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 6.0.3 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2.
What
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, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 6.0.3 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2.
Why
The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
What
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, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 6.0.3 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2.
Why
The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No confirmed evidence
No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material ?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.Reference recorded
CISA Vulnrichment records proof-of-concept exploitation in its SSVC data. BlackTree has not independently executed or validated exploit material.
Likely attack path
a network path → Missing Release of Resource after Effective Lifetime → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness ?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-772: Missing Release of Resource after Effective Lifetime. The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.
CVSS vector ?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedDenial of serviceCWE-772Public exploit reference
A
Official authority intelligence
Only matched European and national findings are included. Language selectors and unavailable sources are omitted.
ENISA EUVD · EUVD-2026-69381Official EUVD mapping
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, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 6.0.3 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2.
Official EUVD recordBSI · German · WID-SEC-W-2026-3146Erlang/OTP: Mehrere Schwachstellen
Ein Angreifer kann mehrere Schwachstellen in Erlang/OTP ausnutzen, um Sicherheitsvorkehrungen zu umgehen, Daten zu manipulieren oder offenzulegen oder einen Denial-of-Service-Zustand auszulösen.
Official advisoryCSIRT Italia · Italian · otp-3Rilevate vulnerabilità in Erlang/OTP
Rilevate molteplici vulnerabilità di sicurezza, di cui 11 con gravità "alta", in diversi componenti di Erlang/OTP, piattaforma open source basata sul linguaggio Erlang e sul relativo set di librerie OTP, utilizzata per lo sviluppo di sistemi distribuiti ad alta disponibilità.
Operational remediation based on structured source evidence.
Status ?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
erlang-asn1 as a component of Red Hat OpenStack Platform 16.2; erlang-compiler as a component of Red Hat OpenStack Platform 16.2; erlang-crypto as a component of Red Hat OpenStack Platform 16.2; erlang-eldap as a component of Red Hat OpenStack Platform 16.2; erlang-erts as a component of Red Hat OpenStack Platform 16.2; erlang-hipe as a component of Red Hat OpenStack Platform 16.2; erlang-inets as a component of Red Hat OpenStack Platform 16.2; erlang-kernel as a component of Red Hat OpenStack Platform 16.2; erlang-mnesia as a component of Red Hat OpenStack Platform 16.2; erlang-os_mon as a component of Red Hat OpenStack Platform 16.2; erlang-parsetools as a component of Red Hat OpenStack Platform 16.2; erlang-public_key as a component of Red Hat OpenStack Platform 16.2; erlang-runtime_tools as a component of Red Hat OpenStack Platform 16.2; erlang-sasl as a component of Red Hat OpenStack Platform 16.2; erlang-snmp as a component of Red Hat OpenStack Platform 16.2; erlang-ssl as a component of Red Hat OpenStack Platform 16.2; erlang-stdlib as a component of Red Hat OpenStack Platform 16.2; erlang-syntax_tools as a component of Red Hat OpenStack Platform 16.2; erlang-tools as a component of Red Hat OpenStack Platform 16.2; erlang-xmerl as a component of Red Hat OpenStack Platform 16.2; erlang.src as a component of Red Hat OpenStack Platform 16.2; erlang-asn1 as a component of Red Hat OpenStack Platform 17.1; erlang-compiler as a component of Red Hat OpenStack Platform 17.1; erlang-crypto as a component of Red Hat OpenStack Platform 17.1; erlang-eldap as a component of Red Hat OpenStack Platform 17.1; erlang-erts as a component of Red Hat OpenStack Platform 17.1; erlang-inets as a component of Red Hat OpenStack Platform 17.1; erlang-kernel as a component of Red Hat OpenStack Platform 17.1; erlang-mnesia as a component of Red Hat OpenStack Platform 17.1; erlang-os_mon as a component of Red Hat OpenStack Platform 17.1; and 11 more
Fixed
erlang27-main@aarch64 as a component of Red Hat Hardened Images; erlang27-main@src as a component of Red Hat Hardened Images; erlang27-main@x86_64 as a component of Red Hat Hardened Images
Action
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 1 Sept 2026 · Last source change 8 Sept 2026, 01:08 UTC · CWE-772 · Missing Release of Resource after Effective Lifetime
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source ?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.FIRST · tracked since 2026-09-02
European sourceENISA EUVD · EUVD-2026-69381
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD not scheduled
Core structured fields are present and their contributing authorities are shown above.
Affected versionsThe structured affected or fixed version information changed.
Before
After
erlang-asn1 as a component of Red Hat OpenStack Platform 16.2; erlang-compiler as a component of Red Hat OpenStack Platform 16.2; erlang-crypto as a component of Red Hat OpenStack Platform 16.2; erlang-eldap as a component of Red Hat OpenStack Platform 16.2; erlang-erts as a component of Red Hat OpenStack Platform 16.2; erlang-hipe as a component of Red Hat OpenStack Platform 16.2; erlang-inets as a component of Red Hat OpenStack Platform 16.2; erlang-kernel as a component of Red Hat OpenStack Platform 16.2; erlang-mnesia as a component of Red Hat OpenStack Platform 16.2; erlang-os_mon as a component of Red Hat OpenStack Platform 16.2; erlang-parsetools as a component of Red Hat OpenStack Platform 16.2; erlang-public_key as a component of Red Hat OpenStack Platform 16.2; erlang-runtime_tools as a component of Red Hat OpenStack Platform 16.2; erlang-sasl as a component of Red Hat OpenStack Platform 16.2; erlang-snmp as a component of Red Hat OpenStack Platform 16.2; erlang-ssl as a component of Red Hat OpenStack Platform 16.2; erlang-stdlib as a component of Red Hat OpenStack Platform 16.2; erlang-syntax_tools as a component of Red Hat OpenStack Platform 16.2; erlang-tools as a component of Red Hat OpenStack Platform 16.2; erlang-xmerl as a component of Red Hat OpenStack Platform 16.2; erlang.src as a component of Red Hat OpenStack Platform 16.2; erlang-asn1 as a component of Red Hat OpenStack Platform 17.1; erlang-compiler as a component of Red Hat OpenStack Platform 17.1; erlang-crypto as a component of Red Hat OpenStack Platform 17.1; erlang-eldap as a component of Red Hat OpenStack Platform 17.1; erlang-erts as a component of Red Hat OpenStack Platform 17.1; erlang-inets as a component of Red Hat OpenStack Platform 17.1; erlang-kernel as a component of Red Hat OpenStack Platform 17.1; erlang-mnesia as a component of Red Hat OpenStack Platform 17.1; erlang-os_mon as a component of Red Hat OpenStack Platform 17.1; and 11 more · Fixed: erlang27-main@aarch64 as a component of Red Hat Hardened Images; erlang27-main@src as a component of Red Hat Hardened Images; erlang27-main@x86_64 as a component of Red Hat Hardened Images
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
CVE-2026-69664: httpd parks a request worker indefinitely on a malformed chunk size sent after the headers | BlackTree