CyberSecBulletin
CVE-2023-45239NVD status: Modified

tac_plus: Improper Filtering of Special Elements

Published Updated By the CyberSecBulletin desk

CVE-2023-45239 is a critical-severity improper filtering of special elements vulnerability in tac_plus from Meta, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 4fdf178 as the first without the flaw, so updating tac_plus to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 2.26% chance of exploitation within 30 days, higher than 83% of scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update tac_plus to 4fdf178 or a later version.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. 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
Metatac_plusbefore 4fdf1784fdf178
Fedora ProjectFedora39Not stated

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
LowNo special conditions are needed; the attack works reliably.
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:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Official description

A lack of input validation exists in tac_plus prior to commit 4fdf178 which, when pre or post auth commands are enabled, allows an attacker who can control the username, rem-addr, or NAC address sent to tac_plus to inject shell commands and gain remote code execution on the tac_plus server.

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

The underlying weakness: Improper Filtering of Special Elements

The product receives data from an upstream component, but it does not filter or incorrectly filters special elements before sending it to a downstream component.

More Improper Filtering of Special Elements vulnerabilities (CWE-790)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Patches and release notes

Third-party and government advisories

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