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NVD / CVE Program· CNA GitHub_M

CVE-2026-55891: PrivateBin: Reflected JSON injection in backend responses via unescaped REQUEST_URI

CVSS 0.0 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.53% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: PrivateBin PrivateBin 2.0.5.

Low priority for now. Upgrade to PrivateBin PrivateBin 2.0.5 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

PrivateBin is an online pastebin where the server has zero knowledge of pasted data. Prior to 2.0.5, Request::getRequestUri() in lib/Request.php passes $_SERVER['REQUEST_URI'] through FILTER_SANITIZE_URL, which does not remove quotation marks, angle brackets, or apostrophes, and Controller::_init() stores the attacker-controlled value in Controller::$_urlBase. Controller::_jsonld() in lib/Controller.php then uses str_replace() to insert that value without JSON escaping into js/types.jsonld, js/paste.jsonld, and the other JSON-LD templates used by /?jsonld= and /?pasteid. A raw quotation mark delivered by an HTTP client, proxy, or structured-data crawler that does not normalize the request target can break out of the JSON string and inject arbitrary key-value data into a CORS-open application/ld+json response. The jsonld branch in Controller::__construct() returns before _setCacheHeaders(), so the response also lacks X-Content-Type-Options: nosniff, Content Security Policy, X-Frame-Options, and Referrer-Policy. Direct script execution was not demonstrated, but manipulated responses can affect structured-data consumers or combine with less strict clients. This issue is fixed in version 2.0.5.

Published
Aug 28, 2026
Updated
Sep 9, 2026
EPSS
0.5% · 45th percentile

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · 0.0 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
0.0
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-55891

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • PrivateBin PrivateBin

    • < 2.0.5affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Packagistprivatebin/privatebinbefore 2.0.52.0.5

Same product

privatebin: all records

Other highest-scoring records for the same primary product.

  • CVE-2022-24833Persistent Cross-site Scripting (XSS) vulnerability in PrivateBin
    24Monitor
  • CVE-2025-64714PrivateBin's template-switching feature allows arbitrary local file inclusion through path traversal
    23Monitor
  • CVE-2025-62796PrivateBin persistent HTML injection in attachment filename enables redirect and defacement
    23Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2024-39899Jul 9, 2024 · PrivateBin allows shortening of URLs for other domains
    21Monitor
  • ← EarlierCVE-2025-64711Nov 13, 2025 · PrivateBin vulnerable to malicious filename use for self-XSS / HTML injection locally for users
    21Monitor
  • ← EarlierCVE-2026-55696Aug 28, 2026 · PrivateBin: Stored Cross-Side-Scripting (XSS) vulnerability in attachment download link via dangerous MIME types with required user-interaction
    17Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
PrivateBin PrivateBin2.0.5 · descriptionVendor (CNA)
Packagist:privatebin/privatebin2.0.5Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Not on record for this CVE: researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-116 · Improper Encoding or Escaping of Output

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records