Evidence used
- No CISA KEV confirmation is currently recorded.
- Exploitation requires an existing local or physical foothold with privileges.
- EPSS is 0.25% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2025
CVE-2025-61955High confidence
F5OS vulnerability
F5 · F5OS - Appliance
Official source article: F5 K000156771 ↗. Check the applicable product and release in the original source.
8.5HighCVSS 4.0
Within 7 days
Mitigation availableHigh technical severity; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:Medium, lowered one band.downgradedsince 26 Feb 2026
Compensating controls
- Apply the linked authoritative mitigation while planning the permanent fix.
- Restrict local access and enforce least privilege on affected hosts.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs F5 F5OS - Appliance and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Mitigation available01
What, why and how
A vulnerability exists in F5OS-A and F5OS-C systems that may allow an authenticated attacker with local access to escalate their privileges. A successful exploit may allow the attacker to cross a security boundary. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
What
A vulnerability exists in F5OS-A and F5OS-C systems that may allow an authenticated attacker with local access to escalate their privileges. A successful exploit may allow the attacker to cross a security boundary. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Why
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes code syntax before using the input in a dynamic evaluation call (e.g. eval).
How
An attacker operating through local access may attempt exploitation with low privileges. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
A vulnerability exists in F5OS-A and F5OS-C systems that may allow an authenticated attacker with local access to escalate their privileges. A successful exploit may allow the attacker to cross a security boundary. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Why
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes code syntax before using the input in a dynamic evaluation call (e.g. eval).
How
An attacker operating through local access may attempt exploitation with low privileges. 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 No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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
- local access → Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection') → cause the confidentiality, integrity or availability impact described by the vendor
- Attack surface
- Local
- Privileges required
- Low: a basic authenticated account is required
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Not a CVSS 4.0 base metric
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-95 ↗
CWE-95: Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection'). The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes code syntax before using the input in a dynamic evaluation call (e.g. eval).
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NCommon Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.
AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.- Post-exploitation / living off the land
- The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
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
- Action
- F5 Networks heeft updates uitgebracht om de kwetsbaarheden te verhelpen. Zie bijgevoegde referenties voor meer informatie. Aanvullend op bovengenoemd beveiligingsadvies heeft F5 Networks een websitebericht gepubliceerd over een beveiligingsincident op hun systemen. F5 Networks adviseert klanten hierin de laatste beveiligingsupdates zo snel mogelijk te installeren. Daarnaast heeft F5 Networks detectie- en hardeningmaatregelen gedeeld, en adviseert het bedrijf deze maatregelen in te zetten. Lees het websitebericht voor meer informatie. **UPDATE 27/01/2026** F5 heeft een update geplaatst op de website betreffende CVE-2025-53521. Het NCSC heeft waargenomen dat er misbruik is gemaakt van deze kwetsbaarheid.
- Workaround
- No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04
Evidence and provenance
Published 15 Oct 2025 · Last source change 26 Feb 2026, 16:57 UTC · CWE-95 · Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2025-34627
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
View recent updates ↗What changed after publication
- Remediation statusRemediation status changed from Awaiting fix to Mitigation available.NCSC-NL ↗
- Before
- Awaiting fix
- After
- Mitigation available
CVE published
Remediation guidance recorded
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.