CyberSecBulletin
CVE-2022-25845NVD status: Modified

com.alibaba:fastjson: Deserialization of Untrusted Data

Published Updated By the CyberSecBulletin desk

CVE-2022-25845 is a critical-severity deserialization of untrusted data vulnerability in com.alibaba:fastjson, 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 1.2.83 as the first without the flaw, so updating com.alibaba:fastjson to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 18.7% chance of exploitation within 30 days, which is in the top 2.68% of all scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update com.alibaba:fastjson to 1.2.83 or a later version.
  2. Update Fastjson to 1.2.83 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
Com.alibaba:fastjsoncom.alibaba:fastjsonbefore 1.2.831.2.83
AlibabaFastjsonbefore 1.2.831.2.83
OracleCommunications Cloud Native Core Unified Data Repository22.2.0Not 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.

Scoring systemScoreSeverityScored by
CVSS 3.18.1HighCNA (snyk.io)
CVSS 3.19.8CriticalNVD
CVSS 2.06.8MediumNVD

Official description

The package com.alibaba:fastjson before 1.2.83 are vulnerable to Deserialization of Untrusted Data by bypassing the default autoType shutdown restrictions, which is possible under certain conditions. Exploiting this vulnerability allows attacking remote servers. Workaround: If upgrading is not possible, you can enable [safeMode](https://github.com/alibaba/fastjson/wiki/fastjson_safemode).

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

The underlying weakness: Deserialization of Untrusted Data

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

How developers prevent this class of flaw

  • If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
  • When deserializing data, populate a new object rather than just deserializing. The result is that the data flows through safe input validation and that the functions are safe.
  • Explicitly define a final object() to prevent deserialization.

More Deserialization of Untrusted Data vulnerabilities (CWE-502)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Technical write-ups (may include proof of concept)

Recent Deserialization of Untrusted Data vulnerabilities

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