CyberSecBulletin
CVE-2026-102062NVD status: Awaiting Analysis

Junos OS: Use of Externally-Controlled Format String

Published Updated By the CyberSecBulletin desk

CVE-2026-102062 is a high-severity use of externally-controlled format string vulnerability in Junos OS from Juniper Networks, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5 as the first without the flaw, so updating Junos OS to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.41% 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 Junos OS to 23.2R2-S7.7 or 23.4R2-S8.13 or 24.2R2-S5.5 or 24.4R2-S5, whichever matches your release line, or a later version.
  2. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Juniper NetworksJunos OSbefore 23.2R2-S7.7; 23.4 up to, but not including, 23.4R2-S8.13; 24.2 up to, but not including, 24.2R2-S5.5; 24.4 up to, but not including, 24.4R2-S5; 25.2 up to, but not including, 25.2R2-S2; 25.4 up to, but not including, 25.4R1-S3; 26.2 up to, but not including, 26.2R1-S223.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S5, 25.2R2-S2, 25.4R1-S3

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
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
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:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (juniper.net).

Scoring systemScoreSeverityScored by
CVSS 4.09.2CriticalCNA (juniper.net)
CVSS 3.18.1HighCNA (juniper.net)

Official description

An Use of Externally-Controlled Format String vulnerability in the ipfd daemon of Juniper Networks Junos OS on SRX Series allows an unauthenticated network-based attacker to execute code with root privileges via a compromised or impersonated configured HTTPS feed server.

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

The underlying weakness: Use of Externally-Controlled Format String

The product uses a function that accepts a format string as an argument, but the format string originates from an external source.

How developers prevent this class of flaw

  • Choose a language that is not subject to this flaw.
  • Ensure that all format string functions are passed a static string which cannot be controlled by the user, and that the proper number of arguments are always sent to that function as well. If at all possible, use functions that do not support the %n operator in format strings.
  • Run compilers and linkers with high warning levels, since they may detect incorrect usage.

More Use of Externally-Controlled Format String vulnerabilities (CWE-134)

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 Junos OS

All Junos OS vulnerabilities

Recent Use of Externally-Controlled Format String vulnerabilities

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