CVE-2023-1999 | Use after free in libwebp

There exists a use after free/double free in libwebp. An attacker can use the ApplyFiltersAndEncode() function and loop through to free best.bw and assign best = trial pointer. The second loop will then return 0 because of an Out of memory error in VP8 encoder, the pointer is still assigned to trial and the AddressSanitizer will attempt a double free.

Published: 2023-06-20 Last update: 2025-02-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2023-1999 is rated Moderate Risk (41.6/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.36%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-1999

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-16 0.34% 0.36% +0.02%
2 2026-04-15 0.41% 0.34% -0.07%
3 2025-12-22 — 0.41% —

Full EPSS history (23 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-1999

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/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:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 1.6 3.6 [email protected]
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H 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:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2023-1999

OS Trackers for CVE-2023-1999

vendor priority summary link
alpine — CVE-2023-1999: 2 source package rows (firefox-esr, libwebp); 14 state rows across 13 repos (3.17-main, 3.18-community, 3.18-main, 3.19-community, 3.19-main, 3.20-community, 3.20-main, 3.21-community, 3.21-main, 3.22-community, 3.22-main, edge-community, edge-main); fixed 14, open 0. https://security.alpinelinux.org/vuln/CVE-2023-1999
debian not yet assigned CVE-2023-1999 not yet assigned priority: Debian including 4 source packages (firefox, firefox-esr, libwebp, thunderbird), 16 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 16. https://security-tracker.debian.org/tracker/CVE-2023-1999
gentoo normal CVE-2023-1999: 3 GLSA(s) (202305-35, 202305-36, 202309-05), 5 atom(s) (mail-client/thunderbird, mail-client/thunderbird-bin, media-libs/libwebp, www-client/firefox, www-client/firefox-bin); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-1999
redhat high — https://access.redhat.com/security/cve/CVE-2023-1999
suse high CVE-2023-1999 severity important: SUSE including 317 source package names (0.3.2-1.2:libwebp7-1.0.3-150200.3.5.1, 0.3.2-1.2:libwebpdemux2-1.0.3-150200.3.5.1, …), 536 product×package rows across 119 product lines (Container containers/lmcache-vllm-openai, Container containers/open-webui, … (119 product lines)): Fixed 305, Known Affected 231. https://www.suse.com/security/cve/CVE-2023-1999/
ubuntu medium CVE-2023-1999 medium priority: Ubuntu including 8 source packages (firefox, libwebp, …), 104 status rows across 13 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 54, ignored 26, released 12, not-affected 9, needs-triage 3. https://ubuntu.com/security/CVE-2023-1999

Affected software / configurations for CVE-2023-1999

Vendor Product Version Raw CPE
webmproject libwebp >= 0.4.2, < 1.3.1 cpe:2.3:a:webmproject:libwebp:*:*:*:*:*:*:*:*

References for CVE-2023-1999

cvelogic Threat Intelligence