VulnerabilityPublished 13 Nov 2026

CVE-2026-128238: secdev scapy · Uncontrolled Recursion

Affects secdev scapySource CVE Database V5

Compare

Not known to be exploited · CVSS 6.9 Medium : upgrade to 2.8.0 when convenient.

Data as of 13 Nov 2026, 09:58 UTC

CVSS 4.0 base score

6.9Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (VulnCheck)	CVSS 4.0	6.9
CNA (VulnCheck)	CVSS 3.1	5.3

Patch: Available – fixed in 2.8.0

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade secdev scapy to 2.8.0.

Affected software

Product	Affected	Fixed in
secdevscapy	Affected <2.8.0	Fixed in 2.8.0
PyPIscapy`pkg:pypi/scapy`Other threats	Affected <2.8.0	Fixed in 2.8.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade scapy to version 2.8.0 or later, where this uncontrolled recursion vulnerability has been fixed. No other mitigation is indicated or required.

Description

CVE-2026-128238 is a vulnerability in secdev scapy versions before 2.8.0 involving uncontrolled recursion in the BER/ASN.1 decoder. An unauthenticated remote attacker can send a specially crafted 833-byte packet containing 250 nested ASN.1 SEQUENCE structures to trigger a RecursionError. This error causes parsing applications handling TLS, SNMP, X.509, or LDAP protocols to crash, even when parsing is done with safe=True.

Impact

Exploitation of this vulnerability results in denial of service by crashing applications that parse ASN.1 data in the affected protocols. The crash is caused by an unhandled RecursionError triggered by deeply nested ASN.1 sequences. There is no indication of privilege escalation, data disclosure, or code execution. The impact is limited to service disruption of parsing components.

Summary

The vulnerability exists in the BER/ASN.1 decoder implementation in scapy/asn1/ber.py prior to version 2.8.0. It allows an attacker to cause uncontrolled recursion by sending a single packet with deeply nested ASN.1 SEQUENCE structures, leading to an unhandled RecursionError. This results in termination of parsing processes for several protocols including TLS, SNMP, X.509, and LDAP. The flaw affects all versions from 0 up to but not including 2.8.0. The issue is fixed in scapy version 2.8.0.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 13 Nov 2026, 09:58 UTC

Technical details

References

Community reviews

Related threats