CyberSecBulletin
CVE-2022-24999NVD status: Modified

Qs: Improperly Controlled Modification of Object Prototype Attributes

Published Updated By the CyberSecBulletin desk

CVE-2022-24999 is a high-severity improperly controlled modification of object prototype attributes vulnerability in Qs from Qs Project, with a CVSS 3.1 base score of 7.5 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 6.2.4, 6.3.3, 6.5.3 as the first without the flaw, so updating Qs to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 15.7% chance of exploitation within 30 days, which is in the top 3.09% of all scored CVEs.

Patch this week

EPSS places it among the vulnerabilities most likely to be exploited soon.

What to do

  1. Update Qs to 6.2.4 or 6.3.3 or 6.5.3 or 6.7.3, whichever matches your release line, or a later version.
  2. Update Express to 4.17.3 or a later version.
  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
Qs ProjectQsbefore 6.2.4; 6.3.0 up to, but not including, 6.3.3; 6.5.0 up to, but not including, 6.5.3; 6.7.0 up to, but not including, 6.7.3; 6.8.0 up to, but not including, 6.8.3; 6.9.0 up to, but not including, 6.9.7; 6.10.0 up to, but not including, 6.10.3; 6.4.0; and 1 more ranges6.2.4, 6.3.3, 6.5.3, 6.7.3, 6.8.3, 6.9.7
OpenjsfExpressbefore 4.17.34.17.3
DebianDebian Linux10.0Not stated

Version data comes from NVD's product matching. 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
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.5HighNVD
CVSS 3.17.5HighCISA (ADP)

Official description

qs before 6.10.3, as used in Express before 4.17.3 and other products, allows attackers to cause a Node process hang for an Express application because an __ proto__ key can be used. In many typical Express use cases, an unauthenticated remote attacker can place the attack payload in the query string of the URL that is used to visit the application, such as a[__proto__]=b&a[__proto__]&a[length]=100000000. The fix was backported to qs 6.9.7, 6.8.3, 6.7.3, 6.6.1, 6.5.3, 6.4.1, 6.3.3, and 6.2.4 (and therefore Express 4.17.3, which has "deps: [email protected]" in its release description, is not vulnerable).

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

The underlying weakness: Improperly Controlled Modification of Object Prototype Attributes

The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.

How developers prevent this class of flaw

  • By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
  • By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
  • When handling untrusted objects, validating using a schema can be used.

More Improperly Controlled Modification of Object Prototype Attributes vulnerabilities (CWE-1321)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Patches and release notes

Third-party and government advisories

Technical write-ups (may include proof of concept)

Other vulnerabilities in Qs

All Qs vulnerabilities

Recent Improperly Controlled Modification of Object Prototype Attributes vulnerabilities

Spotted an error? Tell us.