CVE-2021-28965 [High] | Security Vulnerability in Rexml

CVE-2021-28965 is rated Moderate Risk (54.3/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.58%). Review affected assets and schedule remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-05-09	0.36%	0.58%	+0.21%
2	2026-03-04	0.13%	0.36%	+0.23%
3	2026-03-01	—	0.13%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-05-09

0.36%

0.58%

+0.21%

2026-03-04

0.13%

0.36%

+0.23%

2026-03-01

—

0.13%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.5	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	3.9	3.6	[email protected]
5.0	2.0	MEDIUM	`AV:N/AC:L/Au:N/C:N/I:P/A:N` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:N) No availability impact.	10.0	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.5

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N): Service keeps running; no real outage angle.

3.9

3.6

[email protected]

5.0

2.0

MEDIUM

AV:N/AC:L/Au:N/C:N/I:P/A:N Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:N): No availability impact.

10.0

2.9

[email protected]

OS Trackers for CVE-2021-28965

vendor	priority	summary	link
`alpine`	high	CVE-2021-28965: 1 source package rows (ruby); 45 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 10, open 35.	https://security.alpinelinux.org/vuln/CVE-2021-28965
`debian`	not yet assigned	CVE-2021-28965 not yet assigned priority: Debian including 1 source packages (ruby2.7), 1 status rows across 1 suites (bullseye): resolved 1.	https://security-tracker.debian.org/tracker/CVE-2021-28965
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2021-28965
`suse`	medium	CVE-2021-28965 severity moderate: SUSE including 355 source package names (2.17-17.3:libruby2_5-2_5-2.5.9-4.17.1, 2.17-17.3:ruby2.5-2.5.9-4.17.1, …), 1011 product×package rows across 246 product lines (Container bci/ruby, Container suse/rmt-server, … (246 product lines)): Fixed 780, Known Affected 137, Known Not Affected 61, Will Not Fix 33.	https://www.suse.com/security/cve/CVE-2021-28965/
`ubuntu`	medium	CVE-2021-28965 medium priority: Ubuntu including 4 source packages (ruby-rexml, ruby2.3, ruby2.5, ruby2.7), 35 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): DNE 22, released 9, ignored 3, needs-triage 1.	https://ubuntu.com/security/CVE-2021-28965

Affected software / configurations for CVE-2021-28965

Vendor	Product	Version	Raw CPE
ruby-lang	rexml	< 3.2.5	cpe:2.3:a:ruby-lang:rexml::::::ruby::*
ruby-lang	ruby	< 2.6.7	cpe:2.3:a:ruby-lang:ruby::::::::
ruby-lang	ruby	>= 2.7.0, < 2.7.3	cpe:2.3:a:ruby-lang:ruby::::::::
ruby-lang	ruby	>= 3.0.0, < 3.0.1	cpe:2.3:a:ruby-lang:ruby::::::::
fedoraproject	fedora	34	cpe:2.3:o:fedoraproject:fedora:34:::::::*

References for CVE-2021-28965

URL	Tags
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WTVFTLFVCSUE5CXHINJEUCKSHU4SWDMT/
https://security.netapp.com/advisory/ntap-20210528-0003/	Third Party Advisory
https://www.ruby-lang.org/en/news/2021/04/05/xml-round-trip-vulnerability-in-rexml-cve-2021-28965/	Vendor Advisory

URL

CVE-2021-28965

Exploit prediction scoring system (EPSS) score for CVE-2021-28965

Common vulnerability scoring system (CVSS) metrics for CVE-2021-28965

Weakness enumeration for CVE-2021-28965

GitHub Security Advisory for CVE-2021-28965

OS Trackers for CVE-2021-28965

Affected software / configurations for CVE-2021-28965

References for CVE-2021-28965