VulnerabilityPublished 15 Oct 2025Updated 26 Feb 2026

CVE-2025-54858: F5 BIG-IP · Uncontrolled Recursion

Affects F5 BIG-IPSource CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 28% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 15 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
F5 BIG-IP	Affected 15.1.0 – 17.5.0 4 affected builds	Fixed in–

AI-suggested

To mitigate CVE-2025-54858, organizations should first verify if their BIG-IP deployments use Advanced WAF or ASM modules with JSON content profiles containing malformed JSON schemas. Immediate steps include reviewing and correcting JSON schema configurations to ensure they are well-formed and validated before applying security policies. Administrators should avoid deploying policies with unverified or complex JSON schemas that could trigger recursion. Applying vendor patches or updates as soon as they become available is critical, even though no patches are currently listed, monitoring F5 advisories for updates is necessary. As a temporary workaround, disabling or removing JSON content profiles from security policies can reduce exposure. Network-level protections such as rate limiting and anomaly detection can help identify and block malformed requests targeting this vulnerability. Regularly auditing BIG-IP configurations and employing automated schema validation tools can prevent recurrence. Additionally, implementing redundancy and failover mechanisms for BIG-IP devices can minimize service disruption if the bd process terminates unexpectedly. Finally, maintaining up-to-date backups and incident response plans will aid in rapid recovery if exploitation occurs.

Description

When a BIG-IP Advanced WAF or BIG-IP ASM Security Policy is configured with a JSON content profile that has a malformed JSON schema, and the security policy is applied to a virtual server, undisclosed requests can cause the bd process to terminate. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Impact

The primary impact of CVE-2025-54858 is denial of service due to the termination of the bd process in F5 BIG-IP devices. This can cause temporary or prolonged unavailability of the security policy enforcement, potentially exposing protected applications to direct attacks or traffic without inspection. Organizations relying on BIG-IP Advanced WAF or ASM for critical application security may experience service disruptions, degraded security posture, and increased risk of downstream attacks. The vulnerability affects multiple widely deployed BIG-IP versions, increasing the scope of potential impact globally. Since exploitation requires no authentication and can be triggered remotely, attackers can cause outages without prior access. This can lead to operational downtime, loss of customer trust, and potential financial losses. However, the vulnerability does not allow data theft or modification, limiting the impact to availability. The lack of known exploits in the wild suggests limited immediate threat, but the high severity score warrants proactive mitigation. Enterprises in sectors such as finance, healthcare, government, and telecommunications that depend heavily on F5 BIG-IP for application delivery and security are particularly at risk.

CWE-674Uncontrolled Recursion (opens in a new tab)
Class weakness
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
Implementation
Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.
Implementation
Increase the stack size.
Attack patterns
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

my.f5.com/manage/s/article/K000156621 (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Feb 2026, 05:35 UTC

WeaknessesCWE-674

Technical details

References

Community reviews

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