In proxygen from v2024.10.28.00 until v2026.09.28.00, WebTransportImpl::terminateSessionStreams (WebTransportImpl::destroy in releases befo…

published 2026-09-28 41 d ago modified 2026-09-30 39 d ago also EUVD-2026-88545

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits: 0; none known

In proxygen from v2024.10.28.00 until v2026.09.28.00, WebTransportImpl::terminateSessionStreams (WebTransportImpl::destroy in releases before v2025.08.18.00) failed to unregister read callbacks for streams that were no longer open before destroying them. The transport could then invoke a read callback that had been freed.

Patch / fix

fixed in 1 links 1

Facebook proxygen v2026.09.28.00

github.com/facebook/proxygen@479eb55 commit

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-2026-91096 updated 2026-10-31 cvss 7.5

proxygen: proxygen: Denial of Service via use-after-free in WebTransport stream termination

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: 39 d ago (2026-09-30)

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

Facebook proxygen

Classification

Weakness

CWE-416 Use After Free

References

Sources

CVE List CVE-2026-91096
NVD CVE-2026-91096

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.

Summary