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CVE-2023-20051· NVD / CVE Program· CNA cisco

Cisco Packet Data Network Gateway IPsec ICMP Denial of Service Vulnerability

A vulnerability in the Vector Packet Processor (VPP) of Cisco Packet Data Network Gateway (PGW) could allow an unauthenticated, remote attacker to stop ICMP traffic from being processed over an IPsec connection. This vulnerability is due to the VPP improperly handling a malformed packet. An attacker could exploit this vulnerability by sending a malformed Encapsulating Security Payload (ESP) packet over an IPsec connection. A successful exploit could allow the attacker to stop ICMP traffic over an IPsec connection and cause a denial of service (DoS).

HighCVSS 7.5 · v3.1—No exploit No fix recorded

Noroxi analysis

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Published
Apr 5, 2023
Updated
Jun 17, 2026
EPSS
0.9% · 57th percentile
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Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.9%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
7.5
CNA · cisco
5.8
1.7 point gap

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
ciscopacket data network gateway
ciscoasr 5000
ciscoasr 5500
ciscoasr 5700

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • cisco packet data network gatewaybefore 21.28.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (cisco). Independent of NVD's CPE analysis and usually ahead of it.

  • Cisco Cisco ASR 5000 Series Software

    • n/aaffected

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
function expand(node) {  return node.children.map(expand);}

Fixed

ts
const MAX_DEPTH = 32;function expand(node, depth = 0) {  if (depth > MAX_DEPTH) throw new Error("too deep");  return node.children.map((c) => expand(c, depth + 1));}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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