CVE-2023-20135

highpriority · track · 28EPSS 0.001 · 1 %ileDEEURUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.09% (1st) EPSS

CVSS 7 · high

Is it mine?

14 products

Check your exposure

Who says so?

6 sources

cnnvd · enisa_euvd · fstec_bdu · cisco_csaf

EPSS · scored 2026-10-28

A vulnerability in Cisco IOS XR Software image verification checks could allow an authenticated, local attacker to execute arbitrary code on the underlying operating system. This vulnerability is due to a time-of-check, time-of-use (TOCTOU) race condition when an install query regarding an ISO image is performed during an install operation that uses an ISO image. An attacker could exploit this vulnerability by modifying an ISO image and then carrying out install requests in parallel. A successful exploit could allow the attacker to execute arbitrary code on an affected device.

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

FixedCisco IOS XR Softwarecisco_csaf
Cisco has released software updates that address this vulnerability.
https://software.cisco.com

cvss

Technical severity, 0–10. One row per scoring source.

7.0

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5.7–7

v3.17highCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 1 · impact 5.9

v3.17highAV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU

v3.15.7mediumCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:Nsecondary · ENISA EU

v3.15.7mediumCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:Nsecondary · psirt@cisco.com USexploitability 0.5 · impact 5.2

v3.16.4mediumCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)

v3.15.7mediumCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:Nsecondary · Cisco PSIRT US

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: no · Technical Impact: totalcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-367USprimaryCWE-347USCWE-362USCWE-367US

affected products (14)

Products and version ranges known to be affected.

Cisco Cisco IOS XR Softwareall versionscisco_csafUS
Cisco Cisco IOS XR Software≤ 7.5.2enisa_euvdEU
Cisco Cisco IOS XR Software≤ 7.8.2enisa_euvdEU
Cisco Cisco IOS XR Software≤ 7.7.2enisa_euvdEU
Cisco Cisco IOS XR Software≤ 7.5.3enisa_euvdEU
Cisco Cisco IOS XR Software≤ 7.9.1enisa_euvdEU
Cisco Cisco IOS XR Software≤ 7.8.1enisa_euvdEU
Cisco Cisco IOS XR Software≤ 7.7.1enisa_euvdEU
Cisco Cisco IOS XR Software≤ 7.5.4enisa_euvdEU
Cisco Cisco IOS XR Software≤ 7.9.2enisa_euvdEU
Cisco Cisco IOS XR Software≤ 7.7.21enisa_euvdEU
Cisco Systems Inc. Cisco IOS XR≤ 7.10.1fstec_bduRU
cisco ios xr7.5.2 → 7.6nvdUScpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:*
cisco ios xr7.7 → 7.10.1nvdUScpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:*

advisories (2)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2023-2355Cisco IOS XR: Mehrere SchwachstellenDeutsch2023-09-13csaf · cert_bundDE
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.
cisco-sa-lnt-L9zOkBz5Cisco IOS XR Software Image Verification Vulnerability2023-09-13csaf · cisco_csafUS
A vulnerability in Cisco IOS XR Software image verification checks could allow an authenticated, local attacker to execute arbitrary code on the underlying operating system. This vulnerability is due to a time-of-check, time-of-use (TOCTOU) race condition when an install query regarding an ISO image is performed during an install operation that uses an ISO image. An attacker could exploit this vulnerability by modifying an ISO image and then carrying out install requests in parallel. A successful exploit could allow the attacker to execute arbitrary code on an affected device. Cisco has released software updates that address this vulnerability. There are no 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 ["https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75241"].

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cisco_csaf nvd cert_bund NVD CVE.org MITRE

published 2023-09-13modified 2026-06-17

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+1057 more

references (5)

External citations — patches, advisories, analysis.

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