CVE-2026-1691
Published: 30 January 2026
Summary
CVE-2026-1691 is a medium-severity Improper Input Validation (CWE-20) vulnerability in Adlered Bolo-Solo. Its CVSS base score is 5.3 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 38.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and AC-6 (Least Privilege).
Deeper analysis
CVE-2026-1691, published on 2026-01-30, is a deserialization vulnerability (CWE-20, CWE-502) affecting bolo-solo versions up to 2.6.4. The issue resides in the importMarkdownsSync function within the file src/main/java/org/b3log/solo/bolo/prop/BackupService.java, which relies on the SnakeYAML component. It has a CVSS v3.1 base score of 6.3 (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L).
A remote attacker with low privileges can exploit this vulnerability by manipulating inputs to the affected function, triggering unsafe deserialization. Successful exploitation allows limited impacts on confidentiality, integrity, and availability, with no user interaction required and low attack complexity.
Advisories and related discussions, including the initial report, are documented in GitHub issues at https://github.com/bolo-blog/bolo-solo/issues/325 and https://github.com/bolo-blog/bolo-solo/issues/325#issue-3828755519, as well as VulDB entries such as https://vuldb.com/?ctiid.343485, https://vuldb.com/?id.343485, and https://vuldb.com/?submit.741899.
The exploit has been publicly disclosed and may be used by attackers.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-5013
Vulnerability details
A vulnerability has been found in bolo-solo up to 2.6.4. This impacts the function importMarkdownsSync of the file src/main/java/org/b3log/solo/bolo/prop/BackupService.java of the component SnakeYAML. Such manipulation leads to deserialization. The attack may be launched remotely. The exploit has been disclosed to…
more
the public and may be used.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Unsafe deserialization in a public-facing Java web application (SnakeYAML) directly enables remote exploitation of the server for limited C/I/A impact.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly blocks unsafe SnakeYAML deserialization in importMarkdownsSync by requiring validation of untrusted Markdown input before object reconstruction.
Limits which authenticated users can invoke the BackupService function, reducing the attack surface for the low-privilege remote exploit.
Enables monitoring of deserialization-related exceptions or anomalous object graphs originating from the vulnerable BackupService endpoint.