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Full vulnerability report · 2025
CVE-2025-20363High confidence

Cisco IOS — Heap-based Buffer Overflow

Cisco · IOS

Official source article: Cisco CISCO-SA-HTTP-CODE-EXEC-WMFP3H3O ↗. Check the applicable product and release in the original source.

9.0CriticalCVSS 3.1
Recommended action
Within 72 hours

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.

Mitigation available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 6.92% for the current model date.

Compensating controls

  • Apply the linked authoritative mitigation while planning the permanent fix.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Cisco IOS 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 3 daysRemediation target: Within 90 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-2025-31138

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 72 hours

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.

Mitigation available
01

What, why and how

A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure Firewall Threat Defense (FTD) Software, Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an unauthenticated, remote attacker (Cisco ASA and FTD Software) or authenticated, remote attacker (Cisco IOS, IOS XE, and IOS XR Software) with low user privileges to execute arbitrary code on an affected device. This vulnerability is due to improper validation of user-supplied input in HTTP requests. An attacker could exploit this vulnerability by sending crafted HTTP requests to a targeted web service on an affected device after obtaining additional information about the system, overcoming exploit mitigations, or both. A successful exploit could allow the attacker to execute arbitrary code as root, which may lead to the complete compromise of the affected device. For more information about this vulnerability, see the Details ["#details"] section of this advisory.

What

A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure Firewall Threat Defense (FTD) Software, Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an unauthenticated, remote attacker (Cisco ASA and FTD Software) or authenticated, remote attacker (Cisco IOS, IOS XE, and IOS XR Software) with low user privileges to execute arbitrary code on an affected device. This vulnerability is due to improper validation of user-supplied input in HTTP requests. An attacker could exploit this vulnerability by sending crafted HTTP requests to a targeted web service on an affected device after obtaining additional information about the system, overcoming exploit mitigations, or both. A successful exploit could allow the attacker to execute arbitrary code as root, which may lead to the complete compromise of the affected device. For more information about this vulnerability, see the Details ["#details"] section of this advisory.

Why

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

What

A vulnerability in the web services of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure Firewall Threat Defense (FTD) Software, Cisco IOS Software, Cisco IOS XE Software, and Cisco IOS XR Software could allow an unauthenticated, remote attacker (Cisco ASA and FTD Software) or authenticated, remote attacker (Cisco IOS, IOS XE, and IOS XR Software) with low user privileges to execute arbitrary code on an affected device. This vulnerability is due to improper validation of user-supplied input in HTTP requests. An attacker could exploit this vulnerability by sending crafted HTTP requests to a targeted web service on an affected device after obtaining additional information about the system, overcoming exploit mitigations, or both. A successful exploit could allow the attacker to execute arbitrary code as root, which may lead to the complete compromise of the affected device. For more information about this vulnerability, see the Details ["#details"] section of this advisory.

Why

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

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.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Heap-based Buffer Overflow → execute code or commands in the affected security context
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
High: exploitation depends on specific conditions
Security boundary
Changed: exploitation can affect a different security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-122 ↗

CWE-122: Heap-based Buffer Overflow. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

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:H/PR:N/UI:N/S:C/C:H/I:H/A:H

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.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.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.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
NetworkUnauthenticatedRemote code executionCWE-122
A

Official authority intelligence

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

BSI · German · WID-SEC-2025-2142Cisco ASA, FTD, IOS, IOS XE, IOS XR: Mehrere Schwachstellen

Ein entfernter, authentisierter oder anonymer Angreifer kann mehrere Schwachstellen in Cisco ASA (Adaptive Security Appliance), Cisco Secure Firewall Threat Defense, Cisco IOS, Cisco IOS XE und Cisco IOS XR ausnutzen, um die Authentisierung zu umgehen und beliebigen Programmcode mit Administratorrechten auszuführen.

Official advisory ↗
Canadian Centre for Cyber Security · English · AL25-012AL25-012 - Vulnerabilities impacting Cisco ASA and FTD devices – CVE-2025-20333, CVE-2025-20362 and CVE-2025-20363 – Update 2

An Alert is used to raise awareness of a recently identified cyber threat that may impact cyber information assets, and to provide additional detection and mitigation advice to recipients. The Canadian Centre for Cyber Security ("Cyber Centre") is also available to provide additional assistance regarding the content of this Alert to recipients as requested.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20251001Security Bulletin 01 Oct 2025

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 01 Oct 2025, published on 1 October 2025. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-0819Multiples vulnérabilités dans les produits Cisco

De multiples vulnérabilités ont été découvertes dans les produits Cisco. Elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance et un contournement de la politique de sécurité. Cisco indique que les vulnérabilités CVE-2025-20333 et CVE-2025-20362 sont activement exploitées.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2025-015158シスコシステムズの Cisco Adaptive Security Appliance ソフトウェアおよび Cisco Firepower Threat Defense ソフトウェアにおけるヒープベースのバッファオーバーフローの脆弱性

シスコシステムズの Cisco Adaptive Security Appliance ソフトウェアおよび Cisco Firepower Threat Defense ソフトウェアには、ヒープベースのバッファオーバーフローの脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-6590Cisco 제품 보안 업데이트 권고

Cisco Secure Firewall Adaptive Security Appliance(ASA) Software, Cisco Secure Firewall Threat Defense(FTD) Software, Cisco IOS Software, Cisco IOS XE Software 및 Cisco IOS XR Software의 웹 서비스에서 발생하는 원격 코드 실행 취약점(CVE-2025-20363) [4][8]

Official advisory ↗
NCSC-NL · Dutch · NCSC-2025-0298Kwetsbaarheden verholpen in Cisco Secure Firewall ASA en FTD

De kwetsbaarheid met kenmerk CVE-2025-20333, bevindt zich in de wijze waarop de software gebruikersinvoer in HTTP(S)-verzoeken valideert. Een aanvaller met geldige VPN-inloggegevens kan deze kwetsbaarheid misbruiken door speciaal vervaardigde HTTP-verzoeken naar een getroffen apparaat te sturen. Dit kan de aanvaller in staat stellen om willekeurige code uit te voeren met rootrechten, wat mogelijk leidt tot de volledige compromittering van het getroffen apparaat. De kwetsbaarheid met kenmerk CVE-2025-20363, bevindt zich in de wijze waarop de software gebruikersinvoer in HTTP(S)-verzoeken valideert. Een aanvaller kan deze kwetsbaarheid misbruiken door speciaal vervaardigde HTTP-verzoeken te sturen naar een gerichte webservice op een getroffen apparaat, nadat hij aanvullende systeeminformatie heeft verkregen, exploit-mitigaties heeft omzeild, of beide. Een geslaagde exploit kan de aanvaller in staat stellen willekeurige code uit te voeren met rootrechten, wat kan leiden tot de volledige compromittering van het getroffen apparaat. De kwetsbaarheid met kenmerk CVE-2025-20362, bevindt zich in de wijze waarop de software gebruikersinvoer in HTTP(S)-verzoeken valideert. Een aanvaller kan deze kwetsbaarheid misbruiken door speciaal vervaardigde HTTP-verzoeken naar een gerichte webserver op een apparaat te sturen. Een geslaagde exploit kan de aanvaller in staat stellen om zonder authenticatie toegang te krijgen tot een beperkt toegankelijke URL. De kwetsbaarheden met kenmerk CVE-2025-20333 en CVE-2025-20363 zijn ernstig en vereisen onmiddellijke aandacht, aangezien ze kunnen leiden tot ongeautoriseerde controle over de systemen. Aanvallers kunnen deze kwetsbaarheden misbruiken om beveiligingsmaatregelen te omzeilen. Cisco is op de hoogte van pogingen tot misbruik van deze kwetsbaarheid. Er is (nog) geen publieke Proof-of-Concept-code (PoC) of exploit beschikbaar. Het NCSC verwacht dat PoC of Exploits binnen zeer korte termijn beschikbaar gaat komen, waarmee het risico op grootschalig misbruik toeneemt. Het NCSC adviseert met klem om deze updates zo snel mogelijk te installeren.

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.
Mitigation available
Affected
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
The Cyber Centre strongly recommends that organizations running Cisco ASA and FTD products upgrading to a fixed release software version Footnote 5 . Organizations upgrading an ASA 5500-X Series model to 9.12.4.72 or 9.14.4.28 should refer to Cisco’s Bootloader and/or ROMMON Verification Failure procedures Footnote 6 . If the “firmware-update.log” file is found on “disk0:” after upgrading to a fixed release, organizations are encouraged to preserve the log file and notify the Cyber Centre using the contact information below. Instructions regarding transfer of the log file will be provided as part of the follow-up engagement. In addition, the Cyber Centre strongly recommends that organizations review and implement the Cyber Centre’s Top 10 IT Security Actions Footnote 7 . If activity matching the content of this alert is discovered, recipients are encouraged to report via the My Cyber Portal , or email contact@cyber.gc.ca .
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 25 Sept 2025 · Last source change 26 Feb 2026, 17:47 UTC · CWE-122 · Heap-based Buffer Overflow

CVE recordCVE.org · 5.2
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-2025-31138
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched

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

Material change intelligence

What changed after publication

View recent updates ↗
  1. Remediation statusRemediation status changed from Awaiting fix to Mitigation available.
    Before
    Awaiting fix
    After
    Mitigation available
    Canadian Centre for Cyber Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Remediation guidance recorded
ENISA EUVD · EUVD-2025-31138↗Canadian Centre for Cyber Security remediation guidance↗CVE authority or vendor reference · Cisco CISCO-SA-HTTP-CODE-EXEC-WMFP3H3O↗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-2025-20363 · cve.blacktree.nl