CVE-2025-8842: NASM Netwide Assember · Use After Free
Affects NASM Netwide AssemberSource CVE Database V5
Public exploit available · CVSS 4.8 Medium.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:PExploitation evidence
Disclosed: evidence found.
CVE published 11 Aug 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CVSS exploit maturity: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
AI-suggested
- Immediate upgrade or rollback: Organizations should avoid using the affected NASM version 2.17rc0. If possible, revert to a stable, patched version of NASM or wait for an official patch release addressing CVE-2025-8842.
- Restrict local access: Limit user permissions and access to systems where NASM is installed, especially build servers and development machines, to trusted personnel only. Implement strict access controls and monitoring to detect unauthorized local access attempts.
- Use containerization or sandboxing: Run NASM processes in isolated environments to contain potential exploitation effects and prevent privilege escalation from affecting the host system.
- Monitor system logs and behavior: Implement enhanced logging and anomaly detection on systems running NASM to identify suspicious activity indicative of exploitation attempts.
- Code review and build integrity checks: Employ rigorous code signing and integrity verification for binaries produced using NASM to detect any unauthorized modifications potentially caused by exploitation.
- Incident response readiness: Prepare for potential exploitation scenarios by having response plans and forensic capabilities to investigate and remediate incidents involving NASM-related vulnerabilities.
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.