Remote node crash via descriptor heap fragmentation
Published Sep 18, 2025 · Updated Sep 18, 2025
Resource consumption in The Tor Project Tor 0.4.7.0 through 0.4.8.17 allows remote attackers to crash nodes via crafted descriptors. Repeated uploads of small descriptors followed by larger replacements fragment the glibc ptmalloc heap until memory exhaustion triggers an out-of-memory crash or shutdown. Exploitation requires sustained descriptor updates and works reliably against nodes with less than 8 GB of RAM; the published artifact also demonstrates memory-capacity inference through cache-flush timing.
Summary
What happened
Resource consumption in The Tor Project Tor 0.4.7.0 through 0.4.8.17 allows remote attackers to crash nodes via crafted descriptors. Repeated uploads of small descriptors followed by larger replacements fragment the glibc ptmalloc heap until memory exhaustion triggers an out-of-memory crash or shutdown. Exploitation requires sustained descriptor updates and works reliably against nodes with less than 8 GB of RAM; the published artifact also demonstrates memory-capacity inference through cache-flush timing.
The record
- CVE
- CVE-2025-4444
- Published
- Sep 18, 2025
- Updated
- Sep 18, 2025
- Vendor
- The Tor Project
- Product
- Tor
- Classifications
- CWE-404, CWE-400, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 18, 2025CVE publishedPublication date reported by the CVE source.
- Sep 18, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.4.7.0
- Affected versionversion=0.4.7.1
- Affected versionversion=0.4.7.10
- Affected versionversion=0.4.7.11
- Affected versionversion=0.4.7.12
- Affected versionversion=0.4.7.13
- Affected versionversion=0.4.7.14
- Affected versionversion=0.4.7.15
- Affected versionversion=0.4.7.16
- Affected versionversion=0.4.7.2
- Affected versionversion=0.4.7.3
- Affected versionversion=0.4.7.4
- Affected versionversion=0.4.7.5
- Affected versionversion=0.4.7.6
- Affected versionversion=0.4.7.7
- Affected versionversion=0.4.7.8
- Affected versionversion=0.4.7.9
- Affected versionversion=0.4.8.0
- Affected versionversion=0.4.8.1
- Affected versionversion=0.4.8.10
- Affected versionversion=0.4.8.11
- Affected versionversion=0.4.8.12
- Affected versionversion=0.4.8.13
- Affected versionversion=0.4.8.14
- Affected versionversion=0.4.8.15
- Affected versionversion=0.4.8.16
- Affected versionversion=0.4.8.17
- Affected versionversion=0.4.8.2
- Affected versionversion=0.4.8.3
- Affected versionversion=0.4.8.4
- Affected versionversion=0.4.8.5
- Affected versionversion=0.4.8.6
- Affected versionversion=0.4.8.7
- Affected versionversion=0.4.8.8
- Affected versionversion=0.4.8.9
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Tordos descriptor memory-fragmentation proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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