libnfs: Integer Underflow (Wrap or Wraparound)
CVE-2026-57918 is a high-severity integer underflow (wrap or wraparound) vulnerability in libnfs from Sahlberg, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists version 935b8db712b3c6649bc57ddc276526c4a31680de as the first without the flaw, so updating libnfs to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.3% 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
- Update libnfs to 935b8db712b3c6649bc57ddc276526c4a31680de or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Sahlberg | libnfs | before 935b8db712b3c6649bc57ddc276526c4a31680de | 935b8db712b3c6649bc57ddc276526c4a31680de |
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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- 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
- LowPerformance or availability is reduced.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L. Scored by CNA (mitre.org).
Official description
libnfs through 6.0.2 before 935b8db has an xid integer underflow in READ_IOVEC in rpc_read_from_socket in lib/socket.c during a connection to a crafted NFS server, when the expected pdu size exceeds the absolute pdu size from the xid/record-marker.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Underflow (Wrap or Wraparound)
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
More Integer Underflow (Wrap or Wraparound) vulnerabilities (CWE-191)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other vulnerabilities in libnfs
- 7.1 High severity
- 7.1 High severity
Recent Integer Underflow (Wrap or Wraparound) vulnerabilities
- 8.1 High severity
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 9.1 Critical severity
- 7.5 High severity
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