CyberSecBulletin
CVE-2026-41855NVD status: Analyzed

Spring Framework: Deserialization of Untrusted Data

Published Updated By the CyberSecBulletin desk

CVE-2026-41855 is a critical-severity deserialization of untrusted data vulnerability in Spring Framework from Spring, 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 versions 7.0.7.1, 6.2.18.1, 6.1.28 as the first without the flaw, so updating Spring Framework to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.33% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Spring Framework to 7.0.7.1 or 6.2.18.1 or 6.1.28 or 5.3.49, whichever matches your release line, or a later version.
  2. Read the advisory on spring.io 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
SpringSpring Framework7.0.0 up to, but not including, 7.0.7.1; 6.2.0 up to, but not including, 6.2.18.1; 6.1.0 up to, but not including, 6.1.28; 5.3.0 up to, but not including, 5.3.497.0.7.1, 6.2.18.1, 6.1.28, 5.3.49

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 (vmware.com)
CVSS 3.19.8CriticalNVD

Official description

In an untrusted JMS environment, org.springframework.jms.support.converter.MappingJackson2MessageConverter and org.springframework.jms.support.converter.JacksonJsonMessageConverter allow arbitrary class instantiation, which can lead to unauthorized actions via gadget class deserialization. Affected versions: Spring Framework 7.0.0 through 7.0.7; 6.2.0 through 6.2.18; 6.1.0 through 6.1.27; 5.3.0 through 5.3.48.

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. 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 Spring Framework

All Spring Framework vulnerabilities

Recent Deserialization of Untrusted Data vulnerabilities

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