CyberSecBulletin
CVE-2025-61955NVD status: Analyzed

F5OS - Appliance: Improper Neutralization of Directives in Dynamically Evaluated Code

Published Updated By the CyberSecBulletin desk

CVE-2025-61955 is a high-severity improper neutralization of directives in dynamically evaluated code vulnerability in F5OS - Appliance from F5, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 1.8.3, 1.5.4 as the first without the flaw, so updating F5OS - Appliance to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.25% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update F5OS - Appliance to 1.8.3 or 1.5.4, whichever matches your release line, or a later version.
  2. Update F5OS - Chassis to 1.8.2 or 1.6.4, whichever matches your release line, or a later version.
  3. Update F5os-a to 1.5.4 or a later version.
  4. Read the advisory on my.f5.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
F5F5OS - Appliance1.8.0 up to, but not including, 1.8.3; 1.5.0 up to, but not including, 1.5.41.8.3, 1.5.4
F5F5OS - Chassis1.8.0 up to, but not including, 1.8.2; 1.6.0 up to, but not including, 1.6.41.8.2, 1.6.4
F5F5os-a1.5.1 up to, but not including, 1.5.4; 1.8.01.5.4
F5F5os-c1.6.0 through 1.6.2; 1.8.0 up to, but not including, 1.8.21.8.2

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H. Scored by CNA (f5.com).

Scoring systemScoreSeverityScored by
CVSS 4.08.5HighCNA (f5.com)
CVSS 3.18.8HighCNA (f5.com)

Official description

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Neutralization of Directives in Dynamically Evaluated Code

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 developers prevent this class of flaw

  • If possible, refactor your code so that it does not need to use eval() at all.
  • For Python programs, it is frequently encouraged to use the ast.literal_eval() function instead of eval, since it is intentionally designed to avoid executing code. However, an adversary could still cause excessive memory or stack consumption via deeply nested structures, so the python documentation discourages use of ast.literal_eval() on untrusted data.

More Improper Neutralization of Directives in Dynamically Evaluated Code vulnerabilities (CWE-95)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in F5OS - Appliance

All F5OS - Appliance vulnerabilities

Recent Improper Neutralization of Directives in Dynamically Evaluated Code vulnerabilities

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