---
id: CVE-2026-65634
title: >-
  Inefficient algorithmic complexity in the Erlang/OTP asn1 OBJECT IDENTIFIER
  decoder allows a remote unauthenticated attacker to cause denial of service by
  sending a crafted OID during the TLS handshake.


  The BER OID decoder asn1rtt_ber:d…
summary: >-
  Inefficient algorithmic complexity in the Erlang/OTP asn1 OBJECT IDENTIFIER
  decoder allows a remote unauthenticated attacker to cause denial of service by
  sending a crafted OID during the TLS handshake.


  The BER OID decoder asn1rtt_ber:d…
severity: high
cvss: 8.2
cvssVector: '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'
cwe:
  - CWE-407
vendor: Erlang
product: otp
affected:
  - otp >= 17.0 < *
  - asn1 >= 3.0 < *
  - >-
    erlang/otp >= 84adefa331c4159d432d22840663c38f155cd4c1 <
    0fe2c02fdc06fab1c63be9db1a7456993d20f838
published: '2026-09-22'
updated: '2026-09-22'
sourceUpdated: '2026-09-22T19:09:32.273'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-65634'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-65634.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/erlang/otp/commit/0fe2c02fdc06fab1c63be9db1a7456993d20f838
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://github.com/erlang/otp/security/advisories/GHSA-qghx-23m5-r55m'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-65634'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://www.erlang.org/doc/system/versions.html#order-of-versions'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
tags:
  - nvd
  - cve.org
epss: 0.0025
epssPercentile: 0.16711
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-22T10:12:07.686442Z'
cvssSource: cna
ingestedAt: '2026-09-22T09:01:05.605Z'
---

## Overview

Inefficient algorithmic complexity in the Erlang/OTP asn1 OBJECT IDENTIFIER decoder allows a remote unauthenticated attacker to cause denial of service by sending a crafted OID during the TLS handshake.

The BER OID decoder asn1rtt_ber:dec_subidentifiers/3 in lib/asn1/src/asn1rtt_ber.erl and the equivalent PER helper asn1rtt_per_common:dec_subidentifiers/3 in lib/asn1/src/asn1rtt_per_common.erl accumulate a base-128 subidentifier into an unbounded integer using (Av bsl 7) + H per continuation byte. Each shift and addition on the growing accumulator is linear in the number of bits already accumulated, giving quadratic total work in the size of a single subidentifier. The JER helper asn1rtt_jer:json2oid/1 in lib/asn1/src/asn1rtt_jer.erl exhibits the same class of unbounded-integer parsing when decoding a dot-separated OID from JSON. A DER-encoded OBJECT IDENTIFIER with one very large arc (approximately 262 KB of continuation bytes) consumes roughly 13 seconds of CPU on typical hardware.

The vulnerable decoder is generated into every ASN.1 module that contains an OBJECT IDENTIFIER, including OTP-PUB-KEY which is reached during X.509 certificate parsing via public_key:pkix_decode_cert/2. This decoder runs before any signature or trust chain verification, so any Erlang service that parses peer TLS certificates is exposed: the default for TLS clients (which always parse the server certificate) and for mutual-TLS servers (which parse client certificates).

This vulnerability is associated with program files lib/asn1/src/asn1rtt_ber.erl, lib/asn1/src/asn1rtt_per_common.erl and lib/asn1/src/asn1rtt_jer.erl and program routines asn1rtt_ber:dec_subidentifiers/3, asn1rtt_per_common:dec_subidentifiers/3 and asn1rtt_jer:json2oid/1.

This issue affects OTP from OTP 17.0 before OTP 27.3.4.18, OTP 28.5.0.7, and OTP 29.1.1, corresponding to asn1 from 3.0 before 5.3.4.3, 5.4.3.1, and 5.5.2. Whether OTP before OTP 17.0, corresponding to asn1 before 3.0, is affected is unknown.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.