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CVE Record

CVE-2026-23490: pyasn1 has a DoS vulnerability in decoder

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.2, a Denial-of-Service issue has been found that leads to memory exhaustion from malformed RELATIVE-OID with excessive continuation octets. This vulnerability is fixed in 0.6.2.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-23490 is a denial-of-service flaw in the Python pyasn1 library. Malformed ASN.1 data can trigger excessive memory use and make an affected application unavailable. The issue affects pyasn1 versions before 0.6.2 and is fixed in 0.6.2.

Executive priority

Prioritize remediation for internet-facing or message-processing services that parse ASN.1 with pyasn1. This is not described as code execution, but it can cause service outage and should be handled in normal high-severity patch cycles.

Technical view

pyasn1 before 0.6.2 can exhaust memory while decoding malformed RELATIVE-OID values containing excessive continuation octets. The CVSS 3.1 score is 7.5, reflecting network attackability, low complexity, no required privileges or user interaction, and availability impact only.

Likely exposure

Exposure is most likely in Python applications or packaged platforms that include pyasn1 below 0.6.2 and decode ASN.1 data from untrusted or remotely supplied sources. The bundle also cites Debian LTS and multiple Red Hat advisories, indicating downstream distribution relevance.

Exploitation context

The provided bundle does not cite active exploitation, and KEV is false. Public evidence supports a remotely triggerable availability issue, but not confidentiality impact, integrity impact, or confirmed in-the-wild exploitation.

Researcher notes

Focus review on dependency reachability: whether attacker-controlled ASN.1 reaches pyasn1 decoder code. Sources identify RELATIVE-OID decoding and excessive continuation octets as the memory-exhaustion condition, with upstream commit and v0.6.2 release cited as the fix.

Mitigation direction

  • Upgrade pyasn1 to version 0.6.2 or later.
  • Apply Debian or Red Hat vendor updates where pyasn1 is OS-packaged.
  • Check vendor guidance for downstream products that bundle pyasn1.
  • Limit exposure of ASN.1 decoding paths that accept untrusted input until patched.

Validation and detection

  • Inventory Python dependencies for pyasn1 versions below 0.6.2.
  • Check OS package advisories for installed pyasn1 packages.
  • Identify applications that decode ASN.1 data using pyasn1.
  • Confirm patched hosts or builds use pyasn1 0.6.2 or vendor-fixed packages.
Prepared
Confidence
high
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-770: Exact CWE lookup

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cve · low confidence lookup

CVE-2026-23490 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
3ADP providers
45Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6GitHub_M
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-23490Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container
redhat-SADPpyasn1: pyasn1: Denial of Service due to memory exhaustion from malformed RELATIVE-OID
other:Red Hat severity ratingcvssV3_1
  • 2026-01-16T20:03:33.790Z: Reported to Red Hat.
  • 2026-01-16T19:03:36.442Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
pyasn1pyasn1< 0.6.2Listed
Weakness

CWE details

CWE-770

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-770 · source CWE mapping

Allocation of Resources Without Limits or Throttling

Allocation of Resources Without Limits or Throttling represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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