CVE-2025-53856VulnerabilityPublished 15 Oct 2025Updated 26 Feb 2026

CVE-2025-53856: F5 BIG-IP · Incorrect Control Flow Scoping

Affects F5 BIG-IPSource CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 06:26 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 2026-10-26.

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 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 =17.5.0 =17.1.0 =16.1.0 =15.1.0	Fixed in–

AI-suggested

1. Identify affected BIG-IP devices by verifying the presence of the ePVA chip using F5’s knowledge base article K12837 and confirm software versions (15.1.0, 16.1.0, 17.1.0, 17.5.0) in use. 2. Monitor F5’s official channels for patches or firmware updates addressing CVE-2025-53856 and apply them promptly once released. 3. Implement network segmentation and access controls to restrict exposure of BIG-IP management and data plane interfaces to untrusted networks. 4. Deploy rate limiting and traffic filtering to detect and block anomalous or malformed traffic patterns that could trigger the TMM termination. 5. Use redundant BIG-IP devices and failover configurations to maintain service availability during potential disruptions. 6. Conduct regular health checks and monitoring of BIG-IP system logs and performance metrics to detect early signs of TMM instability or crashes. 7. Engage with F5 support for guidance on temporary workarounds or configuration changes that may mitigate the vulnerability until patches are available. 8. Incorporate this vulnerability into incident response plans to ensure rapid detection and remediation if exploitation attempts occur.

Description

When a virtual server, network address translation (NAT) object, or secure network address translation (SNAT) object uses the embedded Packet Velocity Acceleration (ePVA) feature, undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate. To determine which BIG-IP platforms have an ePVA chip refer to K12837: Overview of the ePVA feature https://my.f5.com/manage/s/article/K12837 . Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Impact

The primary impact of CVE-2025-53856 is a denial-of-service condition caused by the unexpected termination of the Traffic Management Microkernel (TMM) on affected F5 BIG-IP devices. This can disrupt critical network traffic management functions, potentially leading to outages of applications and services relying on BIG-IP for load balancing, security, and traffic acceleration. Organizations using BIG-IP with ePVA in environments such as data centers, cloud service providers, financial institutions, telecommunications, and government networks could experience significant operational disruptions. The vulnerability does not compromise confidentiality or integrity but severely impacts availability, which can affect business continuity and service level agreements. Since exploitation requires no authentication or user interaction and can be triggered remotely over the network, attackers could leverage this flaw to cause widespread service interruptions. The absence of known exploits in the wild currently limits immediate risk, but the vulnerability’s characteristics make it a prime target once exploit code becomes available. The impact is magnified in environments where BIG-IP devices are critical network infrastructure components.

References

my.f5.com/manage/s/article/K000156707 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 27 Feb 2026, 05:29 UTC

WeaknessesCWE-705

Technical details

References

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