Superlinear CPU denial of service in Erlang/OTP ASN.1 OBJECT IDENTIFIER decoder

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-65634
StatePUBLISHED
AssignerEEF
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-22 09:17:05 UTC
Updated2026-09-24 21:17:20 UTC
DescriptionInefficient 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.

Risk And Classification

Primary CVSS: v4.0 8.2 HIGH from 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.004180000 probability, percentile 0.334870000 (date 2026-09-25)

Problem Types: CWE-407 | CWE-407 CWE-407 Inefficient Algorithmic Complexity

VersionSourceTypeScoreSeverityVector
4.06b3ad84c-e1a6-4bf7-a703-f496b71e49dbSecondary8.2HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/C...
4.0CNACVSS8.2HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
None
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Erlang OTP affected 17.0 * otp Not specified
CNA Erlang OTP affected 3.0 * otp Not specified
CNA Erlang OTP affected 84adefa331c4159d432d22840663c38f155cd4c1 0fe2c02fdc06fab1c63be9db1a7456993d20f838 git Not specified
CNA Erlang OTP unaffected 0fe2c02fdc06fab1c63be9db1a7456993d20f838 * git Not specified

References

ReferenceSourceLinkTags
github.com/erlang/otp/commit/0fe2c02fdc06fab1c63be9db1a7456993d20f838 6b3ad84c-e1a6-4bf7-a703-f496b71e49db github.com
www.erlang.org/doc/system/versions.html 6b3ad84c-e1a6-4bf7-a703-f496b71e49db www.erlang.org
github.com/erlang/otp/security/advisories/GHSA-qghx-23m5-r55m 6b3ad84c-e1a6-4bf7-a703-f496b71e49db github.com
cna.erlef.org/cves/CVE-2026-65634.html 6b3ad84c-e1a6-4bf7-a703-f496b71e49db cna.erlef.org
osv.dev/vulnerability/EEF-CVE-2026-65634 6b3ad84c-e1a6-4bf7-a703-f496b71e49db osv.dev
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: tynus2 (en)

CNA: Lukas Backström (en)

CNA: John Högberg (en)

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