Affects widely used NGINX in upstream TLS proxy mode; MITM can tamper proxied responses across many deployments.
CVE-2026-1642
MITM on upstream TLS proxy can inject plaintext into proxied responses.
Is CVE-2026-1642 being exploited?
Not confirmed. CVE-2026-1642 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.35% probability of exploitation in the next 30 days.
How severe is CVE-2026-1642?
CVE-2026-1642 is rated High with a CVSS score of 8.2. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-1642?
Yes. A fix has been recorded for CVE-2026-1642. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-1642 affect?
CVE-2026-1642 affects NGINX OSS, NGINX Plus (proxy mode). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-1642?
Upgrade to patched version when released; monitor advisories.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
MITM on upstream TLS proxy can inject arbitrary plaintext into proxied responses, compromising data integrity.
Patch when possible
- affected>= 1.3.0 and < 1.29.5
- affected>= R36 and < R36 P2
- affected>= R35 and < R35 P1
- affected>= R34 and < *
- affected>= R33 and < *
- affected>= R32 and < R32 P4
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.