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CVE-2020-9484

Deserialization of Untrusted Data: Is CVE-2020-9484 real, exploitable, or a false positive? Here's the community verdict.

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signals

public sources

Exploited in wild
Not listed
CISA KEV
Public exploit
PoC (unverified)
Metasploit/EDB/PoC
Base severity
7 High
CVSS
Exploitation prob.
57%
FIRST EPSS
Weakness
CWE-502 · Deserialization of Untrusted Data
CWE

High severity and high exploitation probability. Prioritise remediation.

public exploits

links to sources — we don’t host code
GitHub PoC(5)unverified

Unverified proof-of-concept code has been published. It may or may not be functional — assess before relying on it.

baseline read

auto · not a community verdict

Likely real & worth prioritising

High base severity and a high real-world exploitation probability both point to a genuine, actively targeted issue.

Based on CVSS · FIRST EPSS

Confirm or dispute →
Affected:ApacheDebianOpensuseFedoraprojectCanonicalOracleMcafee

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

When using Apache Tomcat versions 10.0.0-M1 to 10.0.0-M4, 9.0.0.M1 to 9.0.34, 8.5.0 to 8.5.54 and 7.0.0 to 7.0.103 if a) an attacker is able to control the contents and name of a file on the server; and b) the server is configured to use the PersistenceManager with a FileStore; and c) the PersistenceManager is configured with sessionAttributeValueClassNameFilter="null" (the default unless a SecurityManager is used) or a sufficiently lax filter to allow the attacker provided object to be deserialized; and d) the attacker knows the relative file path from the storage location used by FileStore to the file the attacker has control over; then, using a specifically crafted request, the attacker will be able to trigger remote code execution via deserialization of the file under their control. Note that all of conditions a) to d) must be true for the attack to succeed.

References

NVD MITRE CVE.org

Published

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In your experience, is this finding real and exploitable?

awaiting field verdicts
Real, but not a risk here
Not a real issue

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Field notes & remediation

Verdicts are the quick signal. Notes are the evidence and fixes behind them.

  • 0
    Field note · TruePositive EditorialCurated

    Proof-of-concept code is on GitHub. Exploitation has been demonstrated, though it may need adapting to a real target. FIRST EPSS estimates about a 57% chance of exploitation in the next 30 days, which is high relative to most CVEs. It needs local access, so it reads more as a privilege-escalation or post-access risk than a remote one.

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Related CVEs

Same weakness: CWE-502 · Deserialization of Untrusted Data.