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Fencer Vulns
high 8.7

CVE-2026-77620 json

Vector: Unauthenticated denial of service in the `logstash` source via nested compressed frames (stack exhaustion and decompression amplification).

published 2026-09-22 47 d ago modified 2026-09-24 45 d ago also EUVD-2026-84508

cvss
8.7
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits
0
none known

Summary

Vector is a high-performance observability data pipeline. From 0.15.0 until 0.57.0, the logstash source feeds each decompressed frame back into its decoder without limiting nested compression depth. An unauthenticated remote peer that can reach the default 0.0.0.0:5044 listener can send many nested compressed frames, causing recursive decoding that exhausts the worker thread stack and aborts the process. The same nested construction amplifies decompressed input, and process termination can halt log ingestion for every tenant on a shared pipeline. This issue is fixed in version 0.57.0.

Patch / fix

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-77620 updated cvss 7.5

vector: Vector: Denial of service in `logstash` source via nested compressed frames

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
47 d ago

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • vectordotdev vector

Classification

Weakness
  • CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.