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Response snapshot Oct 28, 2026, 20:06 UTC

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VulnerabilityCVE-2026-118261

Echo: Decompress permits unbounded gzip expansion in v4

Echo v4's opt-in Decompress middleware exposed a gzip-decoded request stream without limiting its expanded size. A small compressed request could therefore produce a very large decoded body.

At a glance

Exploited
Not known
Severity
8.2 High (CVSS 4.0)
Chance of exploitation
Not estimated
Sources
2 independent sources

What to do

GitHub lists first patched versions: github.com/labstack/echo/v4: 4.16.1. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-h7wr-284f-5qvc (opens a new tab)

What happened

Impact

Echo v4's opt-in Decompress middleware exposed a gzip-decoded request stream without limiting its expanded size. A small compressed request could therefore produce a very large decoded body. Handlers that read or bind that body could consume excessive memory or CPU, and repeated or concurrent requests could cause denial of service.

The middleware is not enabled by default. A limit on the compressed request size alone does not bound the decompressed size. Applications that already apply an effective body limit after decompression have reduced exposure.

Affected versions and patch

Continue reading

Echo v4 versions through v4.16.0 are affected. Upgrade to [v4.16.1](https://github.com/labstack/echo/releases/tag/v4.16.1).

The patch adds DecompressConfig.MaxDecompressedSize, defaulting to 100 MiB when zero. A value of -1 explicitly disables the limit. Reading beyond the cap returns ErrStatusRequestEntityTooLarge (HTTP 413), including through JSON and XML binding. Bodies exactly at the configured limit remain valid. Streaming enforcement requires callers to handle body-read errors.

[Fix commit](https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421f).

Workarounds

Disable gzip request decompression on exposed routes, or place BodyLimit after Decompress so the application limit applies to decoded bytes. Apply suitable request deadlines and concurrency limits as well.

Credits

Reported by @q490107865. The exact-limit behavior incorporates @Shubham-Padkonde's work in [#3136](https://github.com/labstack/echo/pull/3136).

Affected package ranges reported by GitHub: github.com/labstack/echo/v4: >= 4.0.0, < 4.16.1

Scores and how they were measured

CVSS base severity

8.2

Version 4.0As of

CVSS:4.0/AV:N/AC:L/AT:P/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

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-h7wr-284f-5qvc (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  3. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  4. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  5. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  6. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  7. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  8. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  9. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  10. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  11. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  12. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  13. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  14. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-h7wr-284f-5qvc, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

  15. Primary source

    NVD CVE-2026-118261 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  16. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  17. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 28). Echo: Decompress permits unbounded gzip expansion in v4 (CVE-2026-118261). https://kevwire.com/record/CVE-2026-118261

MLA

"Echo: Decompress permits unbounded gzip expansion in v4 (CVE-2026-118261)." KEVWire, 28 Oct. 2026, kevwire.com/record/CVE-2026-118261.

Chicago

KEVWire. "Echo: Decompress permits unbounded gzip expansion in v4 (CVE-2026-118261)." Last modified October 28, 2026. https://kevwire.com/record/CVE-2026-118261.

Evidence summary (plain text)

Echo: Decompress permits unbounded gzip expansion in v4 (Oct 23, 2026).
Echo v4's opt-in Decompress middleware exposed a gzip-decoded request stream without limiting its expanded size. A small compressed request could therefore produce a very large decoded body. Handlers that read or bind that body could consume excessive memory or CPU, and repeated or concurrent requests could cause denial of service.

The middleware is not enabled by default. A limit on the compressed request size alone does not bound the decompressed size. Applications that already apply an effective body limit after decompression have reduced exposure.
CVSS 8.2 (version 4.0; evidence as of Oct 28, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-118261).
Sources:
GitHub-reviewed advisory GHSA-h7wr-284f-5qvc: https://github.com/advisories/GHSA-h7wr-284f-5qvc
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yNlQxNTo1NzoxMVrOAAVN6w%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yNlQxNTo0ODozOVrOAAe-5A%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yNlQxNDoyMjo1M1rOAAe_oA%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMjoxMzoxOFrOAAf0ZA%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMTozNDoxMFrOAAfmfw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMTozMjowN1rOAAf0Pw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMjowOTo1M1rOAAf0Yw%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMjowODoyMlrOAAf0Yg%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMjowMDoxMlrOAAf0Wg%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMTo0Nzo0OVrOAAf0Tg%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMTo0NzowN1rOAAX6sg%3D%3D
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc&after=Y3Vyc29yOnYyOpK0MjAyNi0xMC0yM1QyMDo1MTozMFrOAAf0Mg%3D%3D
NVD CVE-2026-118261: https://nvd.nist.gov/vuln/detail/CVE-2026-118261
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-28T18:31:08.168Z&lastModEndDate=2026-10-28T20:05:58.019Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-28T17:55:58.678Z&lastModEndDate=2026-10-28T19:30:56.852Z&resultsPerPage=500&startIndex=0
Record ID: CVE-2026-118261.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 28, 2026, 20:05 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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