CVE-2026-32875VulnerabilityPublished 13 Aug 2026Updated 12 Oct 2026

Python lsp server: UltraJSON has an integer overflow handling large indent leads to buffer overflow or infinite loop

Affects python-lsp-serverSource GCVE Database

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Not known to be exploited · CVSS 7.5 High : upgrade to 1.14.0_1 soon.

Data as of 1 Nov 2026, 22:58 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.14.0_1

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 1 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 python-lsp-server to 1.14.0_1.

Affected software

Product	Affected	Fixed in
Homebrewpython-lsp-server`pkg:brew/python-lsp-server`Other threats	Affected >=1.6.0 <1.14.0_1	Fixed in 1.14.0_1

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 ujson version 5.12.0 which fixes the integer overflow/underflow issues and caps the indent parameter to 1000. Users of python-lsp-server should upgrade to a version that includes this fixed ujson version (>=1.14.0_1). If upgrading is not possible, users should avoid passing untrusted or large indent values, use fixed or no indentation, and ensure indent is non-negative and below the threshold calculated as 2^31 divided by the maximum recursion depth.

Description

CVE-2026-32875 is a vulnerability in the UltraJSON (ujson) library used by python-lsp-server where integer overflow or underflow in handling the 'indent' parameter during JSON serialization can cause a segmentation fault (crash) or an infinite loop. This occurs when the product of the indent value and the nested depth exceeds the 32-bit integer limit or when a large negative indent is used. The issue can lead to denial of service. The vulnerability affects python-lsp-server versions >=1.6.0 and <1.14.0_1. A patch is available in ujson 5.12.0 that fixes the overflow and caps the indent value.

Impact

Successful exploitation can cause denial of service by crashing the Python interpreter or causing it to hang in an infinite loop. There is no impact on confidentiality or integrity. The vulnerability requires that untrusted users control the indent parameter without restrictions. The CVSS v3.1 score is 7.5 (high) with attack vector network, low attack complexity, no privileges required, no user interaction, and impact limited to availability.

Summary

The vulnerability arises from integer overflow/underflow in UltraJSON's handling of the 'indent' parameter in functions like ujson.dumps(). When the indent multiplied by the nested depth of the input exceeds INT32_MAX, a segmentation fault occurs. Additionally, large negative indent values can cause an infinite loop due to underflow. Exploitation requires control over the indent parameter with untrusted input and lack of restrictions on indent size. The maintainers fixed the issue in ujson 5.12.0 by promoting integer types to prevent overflow, skipping indentation code for negative indents, and capping indent at 1000. Workarounds include using fixed or no indentation or ensuring indent is non-negative and reasonably small.

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Affected software

Description

AI analysisMachine-generated, updated 18 Sep 2026, 01:31 UTC

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