NVD / CVE Program· CNA GitHub_M

CVE-2026-33416: LIBPNG has use-after-free via pointer aliasing in `png_set_tRNS` and `png_set_PLTE`

Noroxi assessment

Priority: Monitor (action score 30/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 1% (FIRST EPSS); higher than 64.8% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. A user must open a link or visit a page. Special conditions such as timing or configuration are required.
Fixed version: azl3 libpng 1.6.55-1 on Azure Linux 3.0 1.6.56-1; cbl2 libpng 1.6.55-1 on CBL Mariner 2.0 1.6.56-1.

Low priority for now. Upgrade to azl3 libpng 1.6.55-1 on Azure Linux 3.0 1.6.56-1; cbl2 libpng 1.6.55-1 on CBL Mariner 2.0 1.6.56-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. In versions 1.2.1 through 1.6.55, `png_set_tRNS` and `png_set_PLTE` each alias a heap-allocated buffer between `png_struct` and `png_info`, sharing a single allocation across two structs with independent lifetimes. The `trans_alpha` aliasing has been present since at least libpng 1.0, and the `palette` aliasing since at least 1.2.1. Both affect all prior release lines `png_set_tRNS` sets `png_ptr->trans_alpha = info_ptr->trans_alpha` (256-byte buffer) and `png_set_PLTE` sets `info_ptr->palette = png_ptr->palette` (768-byte buffer). In both cases, calling `png_free_data` (with `PNG_FREE_TRNS` or `PNG_FREE_PLTE`) frees the buffer through `info_ptr` while the corresponding `png_ptr` pointer remains dangling. Subsequent row-transform functions dereference and, in some code paths, write to the freed memory. A second call to `png_set_tRNS` or `png_set_PLTE` has the same effect, because both functions call `png_free_data` internally before reallocating the `info_ptr` buffer. Version 1.6.56 fixes the issue.

HighCVSS 7.5 · v3.1—No exploit Fix available

Published: Mar 26, 2026
Updated: Jun 17, 2026
EPSS: 1.0% · 64th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 1.0%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · GitHub_M: 7.5; NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
libpng	libpng	cpe:2.3:a:libpng:libpng

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

libpng libpng1.2.1 and later · before 1.6.56

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

pnggroup libpng
- >= 1.2.1, < 1.6.56affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

+96

Same product

libpng: all records

Other highest-scoring records for the same primary product.

CVE-2010-1205Buffer overflow in pngpread.c in libpng before 1.2.44 and 1.4.x before 1.4.3, as used in progressive applications, might allow remote attack
52Plan
CVE-2017-12652libpng before 1.6.32 does not properly check the length of chunks against the user limit.
40Plan
CVE-2015-8540Integer underflow in the png_check_keyword function in pngwutil.c in libpng 0.90 through 0.99, 1.0.x before 1.0.66, 1.1.x and 1.2.x before 1
37Monitor

Published before and after this one in the same product

← EarlierCVE-2025-28164Jan 27, 2026 · Buffer Overflow vulnerability in libpng 1.6.43-1.6.46 allows a local attacker to cause a denial of service via png_create_read_struct() func
22Monitor
← EarlierCVE-2026-25646Feb 10, 2026 · LIBPNG has a heap buffer overflow in png_set_quantize
33Monitor
Later →CVE-2026-33636Mar 26, 2026 · LIBPNG has ARM NEON Palette Expansion Out-of-Bounds Read on AArch64
30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
azl3 libpng 1.6.55-1 on Azure Linux 3.0	1.6.56-1 · CBL-Mariner Releases	Microsoft (MSRC)
cbl2 libpng 1.6.55-1 on CBL Mariner 2.0	1.6.56-1 · CBL-Mariner Releases	Microsoft (MSRC)
almalinux:firefox	140.9.1-1.el9_7.alma.1 · AlmaLinux:9	Package registry (OSV)
almalinux:firefox-x11	140.9.1-1.el9_7.alma.1 · AlmaLinux:9	Package registry (OSV)
almalinux:java-1.8.0-openjdk	1:1.8.0.492.b09-1.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:java-1.8.0-openjdk-accessibility	1:1.8.0.492.b09-1.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:java-1.8.0-openjdk-accessibility-fastdebug	1:1.8.0.492.b09-1.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:java-1.8.0-openjdk-accessibility-slowdebug	1:1.8.0.492.b09-1.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:java-1.8.0-openjdk-demo	1:1.8.0.492.b09-1.el8 · AlmaLinux:8	Package registry (OSV)
almalinux:java-25-openjdk	1:25.0.3.0.9-1.el10_2 · AlmaLinux:10	Package registry (OSV)
almalinux:java-25-openjdk-crypto-adapter	1:25.0.3.0.9-1.el10_2 · AlmaLinux:10	Package registry (OSV)
almalinux:java-25-openjdk-crypto-adapter-fastdebug	1:25.0.3.0.9-1.el10_2 · AlmaLinux:10	Package registry (OSV)
almalinux:java-25-openjdk-crypto-adapter-slowdebug	1:25.0.3.0.9-1.el10_2 · AlmaLinux:10	Package registry (OSV)
almalinux:java-25-openjdk-demo	1:25.0.3.0.9-1.el10_2 · AlmaLinux:10	Package registry (OSV)
almalinux:libpng	2:1.6.37-12.el9_7.4 · AlmaLinux:9	Package registry (OSV)
almalinux:libpng-devel	2:1.6.37-12.el9_7.4 · AlmaLinux:9	Package registry (OSV)
almalinux:libpng12	1.2.57-7.el8_10 · AlmaLinux:8	Package registry (OSV)
almalinux:libpng15	1.5.30-9.el8_10 · AlmaLinux:8	Package registry (OSV)
almalinux:thunderbird	140.9.1-1.el9_7.alma.1 · AlmaLinux:9	Package registry (OSV)
alpine:libpng	1.6.56-r0 · Alpine:v3.20	Package registry (OSV)
debian:libpng1.6	1.6.39-2+deb12u4 · Debian:12	Package registry (OSV)
opensuse:libpng12	1.2.59-5.1 · openSUSE:Tumbleweed	Package registry (OSV)
opensuse:libpng16	1.6.40-150600.3.17.1 · openSUSE:Leap 15.6	Package registry (OSV)
red hat:firefox	0:140.9.1-1.el8_2 · Red Hat:rhel_aus:8.2::appstream	Package registry (OSV)
red hat:firefox-debuginfo	0:140.9.1-1.el8_2 · Red Hat:rhel_aus:8.2::appstream	Package registry (OSV)
red hat:firefox-debugsource	0:140.9.1-1.el8_2 · Red Hat:rhel_aus:8.2::appstream	Package registry (OSV)
red hat:firefox-x11	0:140.9.1-1.el9_4 · Red Hat:rhel_eus:9.4::appstream	Package registry (OSV)
red hat:libpng	2:1.6.37-12.el9_7.4 · Red Hat:enterprise_linux:9::appstream	Package registry (OSV)
red hat:libpng-debuginfo	2:1.6.37-12.el9_7.4 · Red Hat:enterprise_linux:9::appstream	Package registry (OSV)
red hat:libpng-debugsource	2:1.6.37-12.el9_7.4 · Red Hat:enterprise_linux:9::appstream	Package registry (OSV)

+14

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-3475714 days apartLIBPNG has a yse-after-free in png_set_PLTE, png_set_tRNS and png_set_hIST leading to corrupted chunk data and potential heap information disclosure
17Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
A user must open a link or visit a page.
Special conditions such as timing or configuration are required.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: High
Privileges required: None
User interaction: Required
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

nvd-secondary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

Fix✗ → ✓Sep 28, 2026, 10:46 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/pnggroup/libpng/commit/23019269764e35ed8458e517f1897bd3c54820eb

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records

Ecosystem	Package	Affected range	Fix
AlmaLinux:10	firefox	before 140.9.1-1.el10_1	140.9.1-1.el10_1
AlmaLinux:10	java-21-openjdk	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-demo	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-demo-fastdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-demo-slowdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-devel	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-devel-fastdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-devel-slowdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-fastdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-headless	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-headless-fastdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-headless-slowdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-javadoc	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-javadoc-zip	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-jmods	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-jmods-fastdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-jmods-slowdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-slowdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-src	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-src-fastdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-src-slowdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-static-libs	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-static-libs-fastdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1
AlmaLinux:10	java-21-openjdk-static-libs-slowdebug	before 1:21.0.11.0.10-2.el10_2.alma.1	1:21.0.11.0.10-2.el10_2.alma.1