CVE-2026-103680
Tnef: heap buffer overflow in find_free_number() via numbered-backup suffix generation
A flaw was found in tnef. A heap-based buffer overflow can occur in the find_free_number() function when generating numbered backup suffixes for duplicate filenames. When numbered backups are enabled and file overwriting is disabled, an attacker can supply a specially crafted Transport Neutral Encapsulation Format (TNEF) file with an excessive number of colliding attachment filenames, causing the numeric counter to write past the allocated memory buffer. This issue may result in an application crash, leading to a Denial of Service (DoS), or potentially arbitrary code execution.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
3.1
Tnef: heap buffer overflow in find_free_number() via numbered-backup suffix generation
A flaw was found in tnef. A heap-based buffer overflow can occur in the find_free_number() function when generating numbered backup suffixes for duplicate filenames. When numbered backups are enabled and file overwriting is disabled, an attacker can supply a specially crafted Transport Neutral Encapsulation Format (TNEF) file with an excessive number of colliding attachment filenames, causing the numeric counter to write past the allocated memory buffer. This issue may result in an application crash, leading to a Denial of Service (DoS), or potentially arbitrary code execution.
- Record
CVE-2026-103680- CVSS 3.1
- 3.1 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-787
- Updated
- 2026-11-02
EUVDEUVD-2026-90773
3.1
A flaw was found in tnef. A heap-based buffer overflow can occur in the find_free_number() function when generating numbered backup suffixes for duplicate filenames. When numbered backups are enabled and file overwriting is disabled, an attacker can supply a specially crafted Transport Neutral Encapsulation Format (TNEF) file with an excessive number of colliding attachment filenames, causing the numeric counter to write past the allocated memory buffer. This issue may result in an application crash, leading to a Denial of Service (DoS), or potentially arbitrary code execution.
- Record
EUVD-2026-90773- CVSS 3.1
- 3.1 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-qr96-v34j-wcrq
3.1
A flaw was found in tnef. A heap-based buffer overflow can occur in the find_free_number()...
A flaw was found in tnef. A heap-based buffer overflow can occur in the find_free_number() function when generating numbered backup suffixes for duplicate filenames. When numbered backups are enabled and file overwriting is disabled, an attacker can supply a specially crafted Transport Neutral Encapsulation Format (TNEF) file with an excessive number of colliding attachment filenames, causing the numeric counter to write past the allocated memory buffer. This issue may result in an application crash, leading to a Denial of Service (DoS), or potentially arbitrary code execution.
- Record
GHSA-qr96-v34j-wcrq- CVSS 3.1
- 3.1 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-787
- Updated
- 2026-11-02
NVD
3.1
A flaw was found in tnef. A heap-based buffer overflow can occur in the find_free_number() function when generating numbered backup suffixes for duplicate filenames. When numbered backups are enabled and file overwriting is disabled, an attacker can supply a specially crafted Transport Neutral Encapsulation Format (TNEF) file with an excessive number of colliding attachment filenames, causing the numeric counter to write past the allocated memory buffer. This issue may result in an application crash, leading to a Denial of Service (DoS), or potentially arbitrary code execution.
- Record
CVE-2026-103680- CVSS 3.1
- 3.1 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L - CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Weakness
- CWE-787
- Updated
- 2026-11-02
OSV
3.1
Tnef: heap buffer overflow in find_free_number() via numbered-backup suffix generation
A flaw was found in tnef. A heap-based buffer overflow can occur in the find_free_number() function when generating numbered backup suffixes for duplicate filenames. When numbered backups are enabled and file overwriting is disabled, an attacker can supply a specially crafted Transport Neutral Encapsulation Format (TNEF) file with an excessive number of colliding attachment filenames, causing the numeric counter to write past the allocated memory buffer. This issue may result in an application crash, leading to a Denial of Service (DoS), or potentially arbitrary code execution.
- Record
CVE-2026-103680- CVSS 3.1
- 3.1 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L - Weakness
- CWE-787
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-103680
6.5
A flaw was found in tnef. A heap-based buffer overflow can occur in the find_free_number() function when generating numbered backup suffixes for duplicate filenames. When numbered backups are enabled and file overwriting is disabled, an attacker can supply a specially crafted Transport Neutral Encapsulation Format (TNEF) file with an excessive number of colliding attachment filenames, causing the numeric counter to write past the allocated memory buffer. This issue may result in an application crash, leading to a Denial of Service (DoS), or potentially arbitrary code execution.
- Record
DEBIAN-CVE-2026-103680- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-103680
3.1
A flaw was found in tnef. A heap-based buffer overflow can occur in the find_free_number() function when generating numbered backup suffixes for duplicate filenames. When numbered backups are enabled and file overwriting is disabled, an attacker can supply a specially crafted Transport Neutral Encapsulation Format (TNEF) file with an excessive number of colliding attachment filenames, causing the numeric counter to write past the allocated memory buffer. This issue may result in an application crash, leading to a Denial of Service (DoS), or potentially arbitrary code execution.
- Record
UBUNTU-CVE-2026-103680- CVSS 3.1
- 3.1 Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L - CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
tnefDebian:12 |
All versions, plus listed versions 1.4.18-31.4.18-41.4.18-51.4.18-6 |
None known |
tnefDebian:13 |
All versions, plus listed versions 1.4.18-41.4.18-51.4.18-6 |
None known |
tnefDebian:14 |
All versions, plus listed versions 1.4.18-41.4.18-51.4.18-6 |
None known |
tnefUbuntu:16.04:LTS |
All versions, plus listed versions 1.4.9-11.4.9-1+deb8u2build0.16.04.11.4.9-1+deb8u3build0.16.04.11.4.9-1+deb8u4build0.16.04.1 |
None known |
tnefUbuntu:18.04:LTS |
All versions, plus listed versions 1.4.12-1.2 |
None known |
tnefUbuntu:20.04:LTS |
All versions, plus listed versions 1.4.12-1.21.4.18-1 |
None known |
tnefUbuntu:22.04:LTS |
All versions, plus listed versions 1.4.18-3 |
None known |
tnefUbuntu:24.04:LTS |
All versions, plus listed versions 1.4.18-3 |
None known |
tnefUbuntu:26.10 |
All versions, plus listed versions 1.4.18-5build11.4.18-6 |
None known |
tnefUbuntu:26.04:LTS |
All versions, plus listed versions 1.4.18-51.4.18-5build1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-103680 is a low vulnerability (CVSS 3.1) in Tnef Project Tnef, published October 1, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.32%, the 25th percentile. No source names a fixed version.
References
access.redhat.com/security/cve/CVE-2026-103680
bugzilla.redhat.com/show_bug.cgi?id=2544478
github.com/verdammelt/tnef
nvd.nist.gov/vuln/detail/CVE-2026-103680
github.com/advisories/GHSA-qr96-v34j-wcrq
github.com/CVEProject/cvelistV5/tree/main/cves/2026/103xxx/CVE-2026-103680.json
security-tracker.debian.org/tracker/CVE-2026-103680
ubuntu.com/security/CVE-2026-103680
cve.org/CVERecord?id=CVE-2026-103680