VulnerabilityPublished 13 Mar 2026Updated 16 Mar 2026

CVE-2026-31899: Kozea CairoSVG · Uncontrolled Recursion

Affects Kozea CairoSVGSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High : upgrade to 2.9.0 soon.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.9.0

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 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
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), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 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 CairoSVG and cairosvg to 2.9.0.

Affected software

Product	Affected	Fixed in
KozeaCairoSVG	Affected <2.9.0	Fixed in 2.9.0
PyPIcairosvg`pkg:pypi/cairosvg`Other threats	Affected <2.9.0	Fixed in 2.9.0

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

AI-suggested

To mitigate CVE-2026-31899, organizations should immediately upgrade CairoSVG to version 2.9.0 or later, where the uncontrolled recursion issue has been addressed. If upgrading is not immediately feasible, implement strict input validation to reject SVG files containing recursive <use> elements or excessively nested references. Employ resource limits such as CPU timeouts or process isolation when processing SVG files to prevent a single malicious input from exhausting system resources. Monitor CPU usage patterns and application logs for signs of abnormal resource consumption during SVG processing. Consider sandboxing SVG rendering processes to contain potential denial of service impacts. Additionally, review and harden any web services or APIs that accept SVG uploads to ensure they do not process untrusted files without proper sanitization. Maintain awareness of updates from the Kozea project and security advisories for any patches or mitigations. Finally, educate development and operations teams about the risks of processing untrusted SVG content and incorporate secure coding practices to handle recursive structures safely.

Description

CairoSVG is an SVG converter based on Cairo, a 2D graphics library. Prior to Kozea/CairoSVG has exponential denial of service via recursive <use> element amplification in cairosvg/defs.py. This causes CPU exhaustion from a small input.

Impact

The primary impact of CVE-2026-31899 is a denial of service condition caused by CPU exhaustion, which can render affected systems unresponsive or degrade performance severely. Organizations relying on CairoSVG for SVG rendering or conversion in web services, automated document processing, or graphic pipelines may experience outages or degraded service availability if targeted by this vulnerability. This can disrupt business operations, lead to service downtime, and potentially cause cascading failures in dependent systems. Since the vulnerability does not affect confidentiality or integrity, data breaches are unlikely; however, the availability impact alone can be critical for high-availability environments. Attackers can exploit this vulnerability remotely without authentication or user interaction, increasing the risk of automated or large-scale attacks. The lack of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as public awareness and exploit development may follow. Organizations processing untrusted SVG inputs are particularly vulnerable, including cloud services, content management systems, and graphic design platforms.

CWE-674Uncontrolled Recursion (opens in a new tab)
Class weakness
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
Implementation
Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.
Implementation
Increase the stack size.
Attack patterns
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 21 Mar 2026, 00:39 UTC

Public exploits and detectionGitHub proofs of concept

WeaknessesCWE-674

Technical details

References

Community reviews

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