Code execution via stale ASCII85 decoder state
Published Aug 11, 2023 · Updated Oct 9, 2024
Use-after-free in QPDF 10.0.4 allows context-dependent attackers to execute arbitrary code through a crafted PDF file. Pl_ASCII85Decoder::flush calls the downstream pipeline's write operation before resetting its position state, so an exception leaves stale state that a later write uses after the backing heap object has been freed. Exploitation requires the crafted file to be processed by a path that decodes and rewrites its stream; the published reproducer demonstrates a memory error, while code execution is the CNA-stated consequence.
Summary
What happened
Use-after-free in QPDF 10.0.4 allows context-dependent attackers to execute arbitrary code through a crafted PDF file. Pl_ASCII85Decoder::flush calls the downstream pipeline's write operation before resetting its position state, so an exception leaves stale state that a later write uses after the backing heap object has been freed. Exploitation requires the crafted file to be processed by a path that decodes and rewrites its stream; the published reproducer demonstrates a memory error, while code execution is the CNA-stated consequence.
The record
- CVE
- CVE-2021-25786
- Published
- Aug 11, 2023
- Updated
- Oct 9, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-416, T1203
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 11, 2023CVE publishedPublication date reported by the CVE source.
- Oct 9, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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.
Public exploit references
- QPDF issue 492 poc.zip reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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