VulnerabilityPublished 13 Aug 2026Updated 31 Oct 2026

CVE-2026-59885: pyasn1 · Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of service

Affects mcp-google-sheetsSource GCVE Database

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Mentioned vulnerabilities

CVE-2026-23490

Not known to be exploited · CVSS 7.5 High : upgrade to 0.6.3_4 soon.

Data as of 1 Nov 2026, 01:51 UTC

CVSS 3.1 base score

7.5High

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

Patch: Available – fixed in 0.6.3_4

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, 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: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 13 Aug 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 31 Oct 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 mcp-google-sheets to 0.6.3_4.

Affected software

Product	Affected	Fixed in
Homebrewmcp-google-sheets`pkg:brew/mcp-google-sheets`Other threats	Affected >=0.5.1 <0.6.3_4	Fixed in 0.6.3_4

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

AI-suggested

A patch is available in pyasn1 version 0.6.3_4 that fixes the quadratic complexity issue by implementing linear-time arc accumulation. Users should upgrade to this version or later. As a workaround, limiting the size of untrusted ASN.1 input before decoding can reduce the risk of exploitation.

Description

A quadratic complexity vulnerability exists in the pyasn1 library's processing of OBJECT IDENTIFIER and RELATIVE-OID values during BER/CER/DER decoding and encoding. This flaw allows crafted ASN.1 data with many arcs to cause excessive CPU consumption, leading to denial of service in applications that decode untrusted ASN.1 data such as certificates, LDAP, SNMP, and Kerberos. The issue affects pyasn1 versions from 0.5.1 up to but not including 0.6.3_4. A fix is available in version 0.6.3_4, which improves the arc accumulation to linear time. Limiting the size of untrusted ASN.1 input before decoding can serve as a workaround.

Impact

This vulnerability allows denial of service (DoS) attacks by causing excessive CPU consumption when decoding or encoding ASN.1 data containing OBJECT IDENTIFIER or RELATIVE-OID values with many arcs. Applications that process untrusted ASN.1 data—such as those handling certificates, LDAP, SNMP, or Kerberos—are susceptible to service disruption. There is no impact on confidentiality or integrity, only availability.

Summary

The pyasn1 library's BER/CER/DER decoders and encoders for OBJECT IDENTIFIER and RELATIVE-OID values exhibit quadratic time complexity relative to the number of arcs processed. This inefficiency allows an attacker to craft ASN.1 payloads with many arcs that consume excessive CPU resources during decoding or encoding, resulting in denial of service. The vulnerability affects ObjectIdentifierPayloadDecoder and RelativeOIDPayloadDecoder in the decoder module, and ObjectIdentifierEncoder and RelativeOIDEncoder in the encoder module, with CER and DER codecs inheriting the same behavior. The previously introduced arc-size limit for CVE-2026-23490 does not mitigate this issue as it does not limit the number of arcs. The vulnerability is fixed in pyasn1 version 0.6.3_4, where arc accumulation now runs in linear time.

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Description

AI analysisMachine-generated, updated 1 Nov 2026, 01:51 UTC

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