CVE-2026-56386: Integer underflow and out-of-bounds read in the HTTP/2 server DATA frame parser in Apache bRPC allows an unaut

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HIGH 7.5REMOTEWATCHLIST

CVE-2026-56386 is a high-severity flaw (CVSS 7.5) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Integer underflow and out-of-bounds read in the HTTP/2 server DATA frame parser in Apache bRPC allows an unauthenticated remote attacker to cause denial of service by sending a malformed DATA frame with the PADDED flag set and a zero-length payload. Root Cause: The HTTP/2 DATA frame handler computed the fragment size from the attacker-controlled payload length and, when the PADDED flag was present, decremented the fragment size before ensuring t

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

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	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-125, CWE-191
Published	2026-10-21
Last modified	2026-10-22

Publisher (CNA): Apache Software Foundation

Last updated 2026-10-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Timeline

2026-10-21Published CVE record published
2026-10-22 16:56 UTCUpdated Record last modified

Exact fixes by distribution

Fedora 46 · python-fontconfig · FIXED · 0.6.3-1.fc46 · FEDORA-2026-f92ca8b01f · source

sudo dnf upgrade --advisory=FEDORA-2026-f92ca8b01f

Fedora ELN · valgrind · FIXED · 3.28.0-1.eln159 · FEDORA-2026-c593ef1d15 · source

sudo dnf upgrade --advisory=FEDORA-2026-c593ef1d15

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-2026-56386?

No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.

Is CVE-2026-56386 being exploited?

CVE-2026-56386 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-2026-56386 affect?

CVE-2026-56386 affects affected software. Severity is high (CVSS 7.5). Integer underflow and out-of-bounds read in the HTTP/2 server DATA frame parser in Apache bRPC allows an unauthenticated remote attacker to cause denial of service by sending a malformed DATA frame with the PADDED flag set and a zero-length

How urgent is CVE-2026-56386?

Priority 50/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

References

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