# CVE-2026-16240: PostgreSQL pg_basebackup can use backup manifest content as a format string

Status: published. Published: 2026-11-12. Updated: 2026-11-12.

Use of externally-controlled format string in PostgreSQL pg_basebackup allows an attacker having already compromised a server to achieve disclosure from pg_basebackup memory, via backup manifest bytes.  The vulnerability does not return the improperly-read bytes back to the attacker's server, so a successful attack would need separate implementation-specific secrets for that.  Integrity impact is unlikely; in particular, the applicable formatter does not support %n.  Versions before PostgreSQL 18.7, 17.12, 16.16, 15.20, and 14.25 are affected.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- n/a / PostgreSQL: ≥ 18; < 18.7 (affected, rpm); ≥ 17; < 17.12 (affected, rpm); ≥ 16; < 16.16 (affected, rpm); ≥ 15; < 15.20 (affected, rpm); ≥ 0; < 14.25 (affected, rpm). Source: CNA: PostgreSQL

## Severity and prioritization

- CVSS 3.1: 3.7 (low); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N; source: CNA: PostgreSQL

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-134

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://www.postgresql.org/support/security/CVE-2026-16240/ (CNA: PostgreSQL)

## Provenance

- CNA: PostgreSQL: https://www.cve.org/CVERecord?id=CVE-2026-16240; retrieved 2026-11-12; source updated 2026-11-12

Revision: 67d1b9e3db6dfc8b50f3e91935f0d5d4b1c5c66c42d236ea11bd01b1d6da27c0

Canonical: https://y2.dev/cve/CVE-2026-16240

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.