CVE-2026-55951
Erlang httpc accepts unlimited response headers, enabling BEAM memory exhaustion.
Is CVE-2026-55951 being exploited?
Not confirmed. CVE-2026-55951 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 0.38% probability of exploitation in the next 30 days.
How severe is CVE-2026-55951?
CVE-2026-55951 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-2026-55951?
Yes. A fix has been recorded for CVE-2026-55951. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-55951 affect?
CVE-2026-55951 affects Erlang/OTP before 27.3.4.17, Erlang/OTP 28.0 before 28.5.0.6, Erlang/OTP 29.0 before 29.0.6, inets/httpc client; any app using httpc:request/4,5. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-55951?
Upgrade OTP/inets to fixed releases; avoid/untrust HTTP redirects; limit reachable servers.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote memory exhaustion/DoS of BEAM VM via malicious or redirected HTTP responses with many/large headers.
Patch when possible
- affected< 17.0
- affected>= 17.0 and < 27.3.4.17
- affected>= 28.0 and < 28.5.0.6
- affected>= 29.0 and < 29.0.6
- affected< 5.10
- affected>= 5.10 and < 9.3.2.7
- affected>= 9.4 and < 9.6.2.3
- affected>= 9.7 and < 9.7.2
- affected>= 84adefa331c4159d432d22840663c38f155cd4c1 and < *
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.