Cyber Resilience

CVE-2020-25682

Memory Safety in Fedoraproject Fedora 32 … 33

High EPSSMemory Safety
Published
20 January 2021
Modified
04 November 2025
Patch / advisory
CVSS Score v3.1 8.1
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.71 99.3th percentile
Risk Priority 81 floored blend · peak EPSS

Summary

CVE-2020-25682 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Fedoraproject Fedora. Its CVSS base score is 8.1 (High).

Operationally, ranked in the top 0.7% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability Data

A flaw was found in dnsmasq before 2.83. A buffer overflow vulnerability was discovered in the way dnsmasq extract names from DNS packets before validating them with DNSSEC data. An attacker on the network, who can create valid DNS replies,…

more

could use this flaw to cause an overflow with arbitrary data in a heap-allocated memory, possibly executing code on the machine. The flaw is in the rfc1035.c:extract_name() function, which writes data to the memory pointed by name assuming MAXDNAME*2 bytes are available in the buffer. However, in some code execution paths, it is possible extract_name() gets passed an offset from the base buffer, thus reducing, in practice, the number of available bytes that can be written in the buffer. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

CWE(s)

Related Threats

Likely ATT&CK TechniquesAI

Techniques this vulnerability likely enables, inferred from its description, weakness type, and attributed-actor tradecraft. Confidence is per-technique.

T1190 Exploit Public-Facing Application Initial Accessconfidence: HIGH
Buffer overflow in dnsmasq's DNS packet name extraction enables remote code execution via crafted DNS replies against a public-facing DNS service.
T1055 Process Injection Stealthconfidence: MEDIUM
Successful heap overflow with attacker-controlled data can be leveraged for process injection or arbitrary code execution on the compromised host.
inferred from description + CWE · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2020-25681Same product: Debian Debian Linux
CVE-2023-3180Same product: Debian Debian Linux
CVE-2023-4504Same product: Debian Debian Linux
CVE-2023-1810Same product: Debian Debian Linux
CVE-2023-40569Same product: Debian Debian Linux
CVE-2023-40567Same product: Debian Debian Linux
CVE-2023-4353Same product: Debian Debian Linux
CVE-2023-1812Same product: Debian Debian Linux
CVE-2023-43641Same product: Debian Debian Linux
CVE-2023-4355Same product: Debian Debian Linux

Affected Assets

thekelleys
dnsmasq
≤ 2.83
fedoraproject
fedora
32, 33
debian
debian linux
10.0, 9.0

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)

Validate
Prove the fix (OWASP ASVS)
  • V1.4.1

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-787

Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 full match
prevents

Secure-development practices directly require bounds checking and safe memory handling that prevent heap overflows.

ID.RA-01 partial match
prevents

Vulnerability scanning and recording can discover heap-overflow flaws but does not prevent their introduction in code.

PR.PS-02 partial match
prevents

Timely patching removes known heap-overflow instances after they exist.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

detects

Security testing in development and acceptance can detect heap overflows before release.

prevents

Secure development lifecycle mandates practices that reduce the likelihood of introducing heap overflows.

prevents

Application security requirements can specify bounds-checking and safe memory APIs that mitigate heap overflows.

prevents

Secure architecture and engineering principles include memory-safety and input-validation controls that address heap overflows.

prevents

Secure coding standards directly prescribe techniques (safe functions, bounds checks) that prevent heap-based buffer overflows.

prevents

Change management can enforce review gates that catch unsafe memory operations before deployment.

References