CVE-2025-55181: Sending an HTTP request/response body with greater than 2^31 bytes triggers an infinite loop in proxygen::coro

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2025-55181 is a medium-severity flaw (CVSS 5.3) affecting proxygen. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Sending an HTTP request/response body with greater than 2^31 bytes triggers an infinite loop in proxygen::coro::HTTPQuicCoroSession which blocks the backing event loop and unconditionally appends data to a std::vector per-loop iteration. This issue leads to unbounded memory growth and eventually causes the process to run out of memory.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 78%)
CISA exploited list	No
Weakness	CWE-834
Published	2025-12-02
Last modified	2026-10-18

Publisher (CNA): Facebook, Inc. · Vendor: facebook

Last updated 2026-10-18 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-12-02 22:16 UTCPublished CVE record published
2026-10-18 17:10 UTCUpdated Record last modified

facebook proxygen UPGRADE

Affected: >= 2025.08.25.00 and <= 2025.12.01.00

Fixed in: newer than 2025.12.01.00

Safe to downgrade to: a release before 2025.08.25.00

1. Check installed version

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

2. UPGRADE to newer than 2025.12.01.00 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade proxygen

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 2025.08.25.00 (Debian / Ubuntu)

apt-cache madison proxygen sudo apt install proxygen=<VERSION_BEFORE_2025.08.25.00> sudo apt-mark hold proxygen

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

dnf --showduplicates list proxygen sudo dnf downgrade proxygen-<VERSION_BEFORE_2025.08.25.00> sudo dnf versionlock add proxygen

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-2025-55181?

proxygen: upgrade to newer than 2025.12.01.00. Exact commands for each OS are on this page.

Is CVE-2025-55181 being exploited?

CVE-2025-55181 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-2025-55181 affect?

CVE-2025-55181 affects proxygen. Severity is medium (CVSS 5.3). Sending an HTTP request/response body with greater than 2^31 bytes triggers an infinite loop in proxygen::coro::HTTPQuicCoroSession which blocks the backing event loop and unconditionally appends data to a std::vector per-loop iteration. Th

How urgent is CVE-2025-55181?

Priority 29/100. Remotely exploitable, no login, no user action

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References

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