xdgmime: Heap-based Buffer Overflow
CVE-2026-16118 is a high-severity heap-based buffer overflow vulnerability in xdgmime from Xdg, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. There is no confirmed exploitation so far. EPSS estimates a 0.28% 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 xdgmime you run against the affected versions below, and install the vendor's latest release.
- 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
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
- 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
- NoneNo data is disclosed.
- 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:N/UI:R/S:U/C:N/I:H/A:H. Scored by CNA (redhat.com).
Official description
A flaw was found in xdgmime. A heap-based buffer overflow can be triggered in _xdg_mime_magic_parse_magic_line() in the xdgmimemagic.c file on little-endian systems when an attacker-controlled MIME magic file in a user-writable XDG data location (e.g., in the $XDG_DATA_HOME/mime/magic path) is parsed by an application performing MIME type detection (e.g., via g_content_type_guess()). When performing byte-swap, incorrect pointer arithmetic on the write side causes an out-of-bounds write of 2 bytes, resulting in an application crash or memory corruption.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Heap-based Buffer Overflow
The product writes past the end of a buffer that was allocated on the heap.
How developers prevent this class of flaw
- Pre-design: Use a language or compiler that performs automatic bounds checking.
- Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
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
Other references
- access.redhat.com/errata/RHSA-2026:64799
- access.redhat.com/errata/RHSA-2026:64800
- access.redhat.com/errata/RHSA-2026:66451
- access.redhat.com/errata/RHSA-2026:67956
- access.redhat.com/errata/RHSA-2026:70636
- access.redhat.com/errata/RHSA-2026:71403
- access.redhat.com/errata/RHSA-2026:71404
- access.redhat.com/errata/RHSA-2026:71405
- access.redhat.com/errata/RHSA-2026:72394
- access.redhat.com/errata/RHSA-2026:72395
- access.redhat.com/errata/RHSA-2026:72399
- access.redhat.com/errata/RHSA-2026:72470
- access.redhat.com/errata/RHSA-2026:72475
- access.redhat.com/errata/RHSA-2026:72476
- access.redhat.com/errata/RHSA-2026:72502
Recent Heap-based Buffer Overflow vulnerabilities
- 7.8 High severity
- 9.8 Critical severity
- 7.8 High severity
- 7.5 High severity
- 9.1 Critical severity
- 8.1 High severity
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