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Full vulnerability report · 2023
CVE-2023-20190High confidence

Cisco Cisco IOS XR Software — security vulnerability

Cisco · Cisco IOS XR Software

Official source article: Cisco CISCO-SA-COMP3ACL-VGMP6BQ3 ↗. Check the applicable product and release in the original source.

5.8MediumCVSS 3.1
Recommended action
Within 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 2 Aug 2024

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.71% for the current model date.

Compensating controls

  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Cisco Cisco IOS XR Software and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

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-2023-24369

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

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
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Fix not verified
01

What, why and how

A vulnerability in the classic access control list (ACL) compression feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to bypass the protection that is offered by a configured ACL on an affected device. This vulnerability is due to incorrect destination address range encoding in the compression module of an ACL that is applied to an interface of an affected device. An attacker could exploit this vulnerability by sending traffic through the affected device that should be denied by the configured ACL. A successful exploit could allow the attacker to bypass configured ACL protections on the affected device, allowing the attacker to access trusted networks that the device might be protecting. There are workarounds that address this vulnerability. This advisory is part of the September 2023 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2023 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication .

What

A vulnerability in the classic access control list (ACL) compression feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to bypass the protection that is offered by a configured ACL on an affected device. This vulnerability is due to incorrect destination address range encoding in the compression module of an ACL that is applied to an interface of an affected device. An attacker could exploit this vulnerability by sending traffic through the affected device that should be denied by the configured ACL. A successful exploit could allow the attacker to bypass configured ACL protections on the affected device, allowing the attacker to access trusted networks that the device might be protecting. There are workarounds that address this vulnerability. This advisory is part of the September 2023 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2023 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication .

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

A vulnerability in the classic access control list (ACL) compression feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to bypass the protection that is offered by a configured ACL on an affected device. This vulnerability is due to incorrect destination address range encoding in the compression module of an ACL that is applied to an interface of an affected device. An attacker could exploit this vulnerability by sending traffic through the affected device that should be denied by the configured ACL. A successful exploit could allow the attacker to bypass configured ACL protections on the affected device, allowing the attacker to access trusted networks that the device might be protecting. There are workarounds that address this vulnerability. This advisory is part of the September 2023 release of the Cisco IOS XR Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: September 2023 Semiannual Cisco IOS XR Software Security Advisory Bundled Publication .

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

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

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Changed: exploitation can affect a different security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-264 ↗

CWE-264. Open the MITRE definition for the exact weakness description.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Common Vulnerability Scoring System 3.1: 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.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SChangedScope: The attack can affect a component governed by a different security authority.CNoneConfidentiality impact: No direct loss is represented by this metric.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: 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.
NetworkUnauthenticatedCWE-264Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2023-2355Cisco IOS XR: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Cisco IOS XR ausnutzen, um beliebigen Code auszuführen, Sicherheitsmaßnahmen zu umgehen oder einen Denial-of-Service-Zustand zu verursachen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20230920Security Bulletin 20 Sep 2023

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 20 Sep 2023, published on 20 September 2023. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2023-013063シスコシステムズの Cisco IOS XR における不正な認証に関する脆弱性

シスコシステムズの Cisco IOS XR には、不正な認証に関する脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5995Cisco 제품 보안 업데이트 권고

isco IOS XR | 7.5 | 7.5.4 | | CVE-2023-20233 | Cisco IOS XR | 7.6 | 7.6.3 | | CVE-2023-20233 | Cisco IOS XR | 7.7 | 7.7.21 | | CVE-2023-20233 | Cisco IOS XR | 7.8 | 7.8.2 | | CVE-2023-20233 | Cisco IOS XR | 7.9 | 7.9.1 | | CVE-2023-20191 | Cisco IOS XR | 6.4 ~ 6.6 | 해결 버전으로 마이그레이션 권장 (7.7.21, 7.9.2, 7.10.1) | | CVE-2023-20191 | Cisco IOS XR | 7.0 ~ 7.6 | 해결 버전으로 마이그레이션 권장 및 사용가능한 SMU을 적용 (7.7.21, 7.9.2, 7.10.1) | | CVE-2023-20191 | Cisco IOS XR | 7.7 | 7.7.21 | | CVE-2023-20191 | Cisco IOS XR | 7.8 | 해결 버전으로 마이그레이션 권장 (7.7.21, 7.9.2, 7.10.1) | | CVE-2023-20191 | Cisco IOS XR | 7.9 | 7.9.2 | | CVE-2023-20191 | Cisco IOS XR | 7.10 | 7.10.1 | | CVE-2023-20190 | Cisco IOS XR | 7.2 이하 버전 | 해결 버전으로 마이그레이션 권장 (7.3.5, 7.5.4, 7.8.2, 7.9.1) | | CVE-2023-20190 | Cisco IOS XR | 7.3 | 7.3.5 | | CVE-2023-20190 | Cisco IOS XR | 7.4 | 해결 버전으로 마이그레이션 권장 (7.3.5, 7.5.4, 7.8.2, 7.9.1) | | CVE-2023-20190 | Cisco IOS XR | 7.5 | 7.5.4 | | CVE-2023-20190 | Cisco IOS XR | 7.6 | 해결 버전으로 마이그레이션 권장 (7.3.5, 7.5.4, 7.8.2, 7.9.1) | | CVE-2023-20190 | Cisco IOS XR | 7.7 | 해결 버전으로 마이그레이션 권장 (7.3.5, 7.5.4, 7.8.2, 7.9.1) | | CVE-2023-20190 | Cisco IOS XR | 7.8 | 7.8.2 | | CVE-2023-20190 | Cisco IOS XR | 7.9 | 7.9.1 | ※ 참고사이트에 명시되어 있는 ‘Fixed Software’ 내용을 참고하여 패치 적용 ##### □ 기타 문의사항 o 한국인터넷진흥원 사이버민원센터: 국번없이 118 [참고사이트] [1] https:

Official advisory ↗
03

Patch and workaround

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.
Fix not verified
Affected
Cisco IOS XR Software: 5.2.0, 5.2.1, 5.2.2, 5.2.4, 5.2.3, 5.2.5, 5.2.47, 5.3.0, 5.3.1, 5.3.2, 5.3.3, 5.3.4, 6.0.0, 6.0.1, 6.0.2, 6.1.1, 6.1.2, 6.1.3, 6.1.4, 6.1.12, 6.1.22, 6.1.32, 6.1.36, 6.1.42, 6.2.1, 6.2.2, 6.2.3, 6.2.25, 6.2.11, 6.3.2, 6.3.3, 6.3.15, 6.4.1, 6.4.2, 6.4.3, 6.5.1, 6.5.2, 6.5.3, 6.5.25, 6.5.26, 6.5.28, 6.5.29, 6.5.32, 6.5.33, 6.6.2, 6.6.3, 6.6.25, 6.6.4, 7.0.1, 7.0.2, 7.0.12, 7.0.14, 7.1.1, 7.1.15, 7.1.2, 7.1.3, 6.7.1, 6.7.2, 6.7.3, 6.7.4, 7.2.0, 7.2.1, 7.2.2, 7.3.1, 7.3.15, 7.3.2, 7.3.3, 7.4.1, 7.4.2, 6.8.1, 6.8.2, 7.5.1, 7.5.3, 7.5.2, 7.6.1, 7.6.2, 7.7.1, 7.7.2, 6.9.1, 6.9.2, 7.8.1
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
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 13 Sept 2023 · Last source change 2 Aug 2024, 09:05 UTC · CWE-264

CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2023-24369
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2023-24369↗Public exploit reference · Cisco CISCO-SA-COMP3ACL-VGMP6BQ3↗Official CVE record (CNA and ADP data)↗NVD record↗
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.
Free version - for non-commercial use only.CVE-2023-20190 · cve.blacktree.nl