CVE-2025-49601 [Medium] | Out-of-bounds Read in Mbed Tls

In MbedTLS 3.3.0 before 3.6.4, mbedtls_lms_import_public_key does not check that the input buffer is at least 4 bytes before reading a 32-bit field, allowing a possible out-of-bounds read on truncated input. Specifically, an out-of-bounds read in mbedtls_lms_import_public_key allows context-dependent attackers to trigger a crash or limited adjacent-memory disclosure by supplying a truncated LMS (Leighton-Micali Signature) public-key buffer under four bytes. An LMS public key starts with a 4-byte type indicator. The function mbedtls_lms_import_public_key reads this type indicator before validating the size of its input.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-30	0.06%	0.26%	+0.20%
2	2026-03-20	0.03%	0.06%	+0.02%
3	2025-11-30	—	0.03%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-30

0.06%

0.26%

+0.20%

2026-03-20

0.03%

0.06%

+0.02%

2025-11-30

—

0.03%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
4.8	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L` 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:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. 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:L) Some sensitive info could get out, but not a total data dump. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	2.2	2.5	[email protected]
6.5	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L` 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:L) Some sensitive info could get out, but not a total data dump. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	3.9	2.5	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

4.8

3.1

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L 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:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

2.2

2.5

[email protected]

6.5

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L 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:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

3.9

2.5

[email protected]

OS Trackers for CVE-2025-49601

vendor	priority	summary	link
`alpine`	—	CVE-2025-49601: 1 source package rows (mbedtls); 18 state rows across 4 repos (3.20-main, 3.21-main, 3.22-main, edge-main); fixed 4, open 14.	https://security.alpinelinux.org/vuln/CVE-2025-49601
`debian`	unimportant	CVE-2025-49601 unimportant priority: Debian including 1 source packages (mbedtls), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2025-49601
`ubuntu`	medium	CVE-2025-49601 medium priority: Ubuntu including 1 source packages (mbedtls), 9 status rows across 9 suites (bionic, focal, jammy, noble, oracular, plucky, questing, upstream, xenial): not-affected 5, ignored 2, needed 1, released 1.	https://ubuntu.com/security/CVE-2025-49601

Affected software / configurations for CVE-2025-49601

Vendor	Product	Version	Raw CPE
trustedfirmware	mbed_tls	>= 3.3.0, < 3.6.4	cpe:2.3:a:trustedfirmware:mbed_tls::::::::

References for CVE-2025-49601

URL	Tags
https://github.com/Mbed-TLS/mbedtls-docs/blob/main/security-advisories/mbedtls-security-advisory-2025-06-4.md	Third Party Advisory

URL

CVE-2025-49601

Exploit prediction scoring system (EPSS) score for CVE-2025-49601

Common vulnerability scoring system (CVSS) metrics for CVE-2025-49601

Weakness enumeration for CVE-2025-49601

OS Trackers for CVE-2025-49601

Affected software / configurations for CVE-2025-49601

References for CVE-2025-49601