Netwide Assember: Use After Free
CVE-2025-8842 is a high-severity use after free vulnerability in Netwide Assember from Nasm, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. Affected Netwide Assember versions: 2.17rc0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.27% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Netwide Assember you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on bugzilla.nasm.us for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| NASM | Netwide Assember | 2.17rc0 | Not stated |
| Nasm | Netwide Assembler | 2.17 | Not 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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- 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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 1.9 | Low | CNA (vuldb.com) |
| CVSS 3.1 | 5.3 | Medium | CNA (vuldb.com) |
| CVSS 3.1 | 7.8 | High | NVD |
| CVSS 2.0 | 4.3 | Medium | CNA (vuldb.com) |
Official description
A vulnerability has been found in NASM Netwide Assember 2.17rc0. Affected by this issue is the function do_directive of the file preproc.c. The manipulation leads to use after free. An attack has to be approached locally. The exploit has been disclosed to the public and may be used.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- bugzilla.nasm.us/show_bug.cgi?id=3392933Exploit, Issue Tracking
Third-party and government advisories
- vuldb.com/?id.319376Third Party Advisory, VDB Entry
Technical write-ups (may include proof of concept)
- drive.google.com/file/d/11vEV1vMHXO4BrDGhvWAMm0Qo1woiUwVV/view?usp=drive_linkExploit
- vuldb.com/?submit.623184Exploit, Third Party Advisory, VDB Entry
Other references
- vuldb.com/?ctiid.319376Permissions Required, VDB Entry
Other vulnerabilities in Netwide Assember
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
Recent Use After Free vulnerabilities
- 8.8 High severity
- 7.8 High severity
- 8.8 High severity
- 8.8 High severity
- 7.5 High severity
- 7.0 High severity
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