CVE-2026-49755: Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in wojtekmach Req allows attack

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HIGH 7.5REMOTEUPGRADE

CVE-2026-49755 is a high-severity flaw (CVSS 7.5) affecting req. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in wojtekmach Req allows attacker-controlled HTTP servers to exhaust memory in a Req client via decompression-bomb response bodies. Req's default response pipeline includes Req.Steps.decode_body/1 and Req.Steps.decompress_body/1 in lib/req/steps.ex. decode_body/1 dispatches on the server-supplied content-type (or URL extension) and calls :zip.extract(body, [:memory])

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 52%)
CISA exploited list	No
Weakness	CWE-409
Published	2026-06-08
Last modified	2026-08-18

Publisher (CNA): EEF · Vendor: wojtekmach

Last updated 2026-08-18 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-08 16:16 UTCPublished CVE record published
2026-08-18 15:46 UTCUpdated Record last modified

wojtekmach req UPGRADE

Affected: >= 0.1.0 and < 0.6.1

Fixed in: 0.6.1

Safe to downgrade to: a release before 0.1.0

1. Check installed version

apt-cache policy req || rpm -q req || req --version

2. UPGRADE to 0.6.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade req

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade req

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 0.1.0 (Debian / Ubuntu)

apt-cache madison req sudo apt install req=<VERSION_BEFORE_0.1.0> sudo apt-mark hold req

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list req sudo dnf downgrade req-<VERSION_BEFORE_0.1.0> sudo dnf versionlock add req

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-49755?

req: upgrade to 0.6.1. Exact commands for each OS are on this page.

Is CVE-2026-49755 being exploited?

CVE-2026-49755 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-49755 affect?

CVE-2026-49755 affects req. Severity is high (CVSS 7.5). Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in wojtekmach Req allows attacker-controlled HTTP servers to exhaust memory in a Req client via decompression-bomb response bodies. Req's default response pipel

How urgent is CVE-2026-49755?

Priority 48/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-49756 LOW 3.7 UPGRADE Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in wojtekmach Req allows multipart

References

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