Security Resilience

CVE-2017-6742

Memory Safety in Cisco Ios 12.0 – 12.4

CISA KEVActive ExploitationEUVD ExploitedMemory Safety
Published
17 July 2017
Modified
22 April 2026
KEV Added
19 April 2023
Patch / advisory
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.21 98th percentile
Risk Priority 90 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2017-6742 is a high-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Cisco Ios. Its CVSS base score is 8.8 (High).

Operationally, ranked in the top 2% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

A buffer overflow vulnerability exists in the SNMP implementation on affected Cisco devices, impacting all versions of the protocol including 1, 2c, and 3. The flaw allows an authenticated remote attacker to trigger a system reload or execute arbitrary code by sending a specially crafted SNMP packet directed at the device. The issue stems from improper handling of SNMP traffic and carries a CVSS score of 8.8 with the CWE-119 classification.

An attacker who knows the read-only community string for SNMPv2c or earlier, or valid user credentials for SNMPv3, can exploit the vulnerability to obtain full control of the system or cause a denial-of-service condition through a reload. Exploitation is possible over the network but requires the attacker to direct traffic specifically to the vulnerable device rather than relying on spoofed or broadcast packets.

Cisco security advisories recommend applying the available patches or mitigations referenced in cisco-sa-20170629-snmp, while the listing in the CISA Known Exploited Vulnerabilities catalog indicates confirmed real-world exploitation activity.

EU & UK References

Vulnerability Data

A vulnerability in the SNMP implementation of could allow an authenticated, remote attacker to cause a reload of the affected system or to remotely execute code. An attacker could exploit this vulnerability by sending a crafted SNMP packet to the…

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affected device.  The vulnerability is due to a buffer overflow in the affected code area. The vulnerability affects all versions of SNMP (versions 1, 2c, and 3). The attacker must know the SNMP read only community string (SNMP version 2c or earlier) or the user credentials (SNMPv3). An exploit could allow the attacker to execute arbitrary code and obtain full control of the system or to cause a reload of the affected system. Only traffic directed to the affected system can be used to exploit this vulnerability.

CWE(s)
KEV Date Added
19 April 2023

Related Threats

Threat-Actor AttributionAI

APT28 (G0007)
APT28 Exploits Known Vulnerability to Carry Out Reconnaissance and Deploy Malware on Cisco Routers | CISA
AnonOps
APT28 Exploits Known Vulnerability to Carry Out Reconnaissance and Deploy Malware on Cisco Routers | CISA
Apple Inc. (Masimo pulse-oximetry trade-secret 2020-2024)
2023 Top Routinely Exploited Vulnerabilities | CISA
Microsoft Corp. (Salesforce / Slack engineer recruitment claims)
2023 Top Routinely Exploited Vulnerabilities | CISA
Clop
2023 Top Routinely Exploited Vulnerabilities | CISA

CVEs Like This One

CVE-2017-6738Same product: Cisco Iosboth on KEV
CVE-2017-6743Same product: Cisco Iosboth on KEV
CVE-2017-6737Same product: Cisco Iosboth on KEV
CVE-2017-6736Same product: Cisco Iosboth on KEV
CVE-2017-6739Same product: Cisco Iosboth on KEV
CVE-2017-6740Same product: Cisco Iosboth on KEV
CVE-2017-6663Same product: Cisco Iosboth on KEV
CVE-2023-20109Same product: Cisco Iosboth on KEV
CVE-2017-6627Same product: Cisco Iosboth on KEV
CVE-2017-6744Same product: Cisco Iosboth on KEV

Affected Assets

cisco
ios
12.0 — 12.4 · 15.0 — 15.6
cisco
ios xe
2.2.0 — 3.17

Mitigating Controls

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-119

Ongoing control assessments and code testing (static/dynamic analysis, fuzzing) surface memory buffer restriction failures, which are then remediated before release.

addresses: CWE-119

Managed runtimes used by platform-independent applications (e.g., JVM, CLR) enforce memory safety, preventing most buffer overflows that require direct memory manipulation.

addresses: CWE-119

Memory protections (e.g., W^X, ASLR) make exploitation of buffer-boundary violations far harder to turn into code execution.

addresses: CWE-119

Detects exploitation attempts that produce memory corruption, crashes, or anomalous behavior.

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.

blocks

A.8.25 mandates secure SDLC practices (secure coding guidelines, security requirements, testing including code scans and penetration tests, developer training) that reach buffer management and can stop many buffer overruns from reaching production, but leaves a bounded remainder (e.g. flaws in non-software components, incomplete enforcement of guidelines, or post-deployment changes)

blocks

Application security requirements can specify memory-safety rules, but do not prescribe implementation details.

blocks

A.8.27 mandates security-by-design principles (e.g. least privilege, fail securely, distrust external input, hardening) plus design reviews that can catch and stop buffer-boundary errors before they reach code, but this is only one minority slice of CWE-119's broad surface (language-specific flaws, unsafe library use, compiler/runtime mitigations, and post-deployment instances remain outside its direct scope).

prevents

Secure coding standards explicitly forbid unsafe buffer operations, directly eliminating CWE-119.

finds

Security testing in development catches out-of-bounds accesses before release, covering most instances of the weakness.

Hardening callouts derived

DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.

  • No fine-grained STIG row for CWE-119, a class-level weakness. Rules are authored against its narrower children: CWE-823.

References