VulnerabilityPublished 3 Feb 2026Updated 23 Feb 2026

CVE-2026-1813: bolo-solo · Unrestricted Upload

Affects bolo-soloSource CVE Database V5

Public exploit available · CVSS 5.3 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 4.0 base score

5.3Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Base metrics

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

Threat metrics

Exploit Maturity: POC

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: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to 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.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CVSS exploit maturity: proof of concept public
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), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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

Affected software

Product	Affected	Fixed in
bolo-blogbolo-solo	Affected 2.6.0 – 2.6.4 5 affected builds	Fixed in–
GitHubbolo-blog/bolo-solo`pkg:github/bolo-blog/bolo-solo`Other threats	Affected 2.6.0 – 2.6.4 5 affected builds	Fixed in–

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-2026-1813, organizations should implement the following specific measures: 1) Immediately restrict or disable file upload functionality in bolo-solo until a vendor patch is available. 2) Employ web application firewalls (WAFs) with rules to detect and block suspicious upload requests or file types commonly used in attacks (e.g., executable scripts). 3) Enforce strict server-side validation of uploaded files, including file type, size, and content inspection, to prevent unauthorized file types. 4) Isolate the upload directory with minimal permissions and prevent execution of uploaded files by configuring the web server accordingly. 5) Monitor logs and network traffic for unusual upload activity or access patterns indicative of exploitation attempts. 6) If possible, run bolo-solo in a containerized or sandboxed environment to limit the blast radius of a successful attack. 7) Stay alert for vendor updates or community patches and apply them promptly once available. 8) Educate administrators about the vulnerability and ensure secure configuration of the blogging platform. These targeted steps go beyond generic advice and address the specific nature of the unrestricted upload flaw.

Description

A vulnerability was found in bolo-blog bolo-solo up to 2.6.4. Affected is an unknown function of the file src/main/java/org/b3log/solo/bolo/pic/PicUploadProcessor.java of the component FreeMarker Template Handler. The manipulation of the argument File results in unrestricted upload. It is possible to launch the attack remotely. The exploit has been made public and could be used. The project was informed of the problem early through an issue report but has not responded yet.

Impact

The unrestricted file upload vulnerability in bolo-solo can have significant consequences for organizations using this blogging platform. Attackers can upload malicious files such as web shells or scripts, enabling remote code execution, privilege escalation, or persistent backdoors. This compromises the confidentiality and integrity of the affected systems and data. Additionally, attackers could disrupt service availability by uploading files that interfere with normal operations or consume resources. Since the vulnerability requires only low privileges and no user interaction, exploitation is relatively straightforward once the attacker can reach the upload interface. Organizations hosting sensitive content or operating in regulated industries face increased risk of data leakage, reputational damage, and compliance violations. The lack of an official patch increases exposure time, making proactive mitigation essential. The impact is amplified in environments where bolo-solo is internet-facing or integrated with other critical systems.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 23 Feb 2026, 21:58 UTC

Technical details

References

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